ts
About ................................................................................................................................................................................... 1
Chapter 1: Getting started with VBA ................................................................................................................... 2
Section 1.1: Accessing the Visual Basic Editor in Microsoft Oce ............................................................................. 2
Section 1.2: Debugging .................................................................................................................................................. 3
Section 1.3: First Module and Hello World ................................................................................................................... 4
Chapter 2: Comments ................................................................................................................................................. 6
Section 2.1: Apostrophe Comments ............................................................................................................................. 6
Section 2.2: REM Comments ........................................................................................................................................ 6
Chapter 3: String Literals - Escaping, non-printable characters and line-continuations
................................................................................................................................................................................................. 7
Section 3.1: Escaping the " character ........................................................................................................................... 7
Section 3.2: Assigning long string literals .................................................................................................................... 7
Section 3.3: Using VBA string constants ..................................................................................................................... 7
Chapter 4: VBA Option Keyword .......................................................................................................................... 9
Section 4.1: Option Explicit ............................................................................................................................................ 9
Section 4.2: Option Base {0 | 1} .................................................................................................................................. 10
Section 4.3: Option Compare {Binary | Text | Database} ........................................................................................ 12
Chapter 5: Declaring Variables ........................................................................................................................... 14
Section 5.1: Type Hints ................................................................................................................................................ 14
Section 5.2: Variables .................................................................................................................................................. 15
Section 5.3: Constants (Const) ................................................................................................................................... 18
Section 5.4: Declaring Fixed-Length Strings ............................................................................................................. 19
Section 5.5: When to use a Static variable ............................................................................................................... 20
Section 5.6: Implicit And Explicit Declaration ............................................................................................................ 22
Section 5.7: Access Modifiers ..................................................................................................................................... 22
Chapter 6: Declaring and assigning strings .................................................................................................. 24
Section 6.1: Assignment to and from a byte array .................................................................................................. 24
Section 6.2: Declare a string constant ...................................................................................................................... 24
Section 6.3: Declare a variable-width string variable .............................................................................................. 24
Section 6.4: Declare and assign a fixed-width string .............................................................................................. 24
Section 6.5: Declare and assign a string array ........................................................................................................ 24
Section 6.6: Assign specific characters within a string using Mid statement ........................................................ 25
Chapter 7: Concatenating strings ...................................................................................................................... 26
Section 7.1: Concatenate an array of strings using the Join function ................................................................... 26
Section 7.2: Concatenate strings using the & operator ........................................................................................... 26
Chapter 8: Frequently used string manipulation ....................................................................................... 27
Section 8.1: String manipulation frequently used examples ................................................................................... 27
Chapter 9: Substrings ............................................................................................................................................... 29
Section 9.1: Use Left or Left$ to get the 3 left-most characters in a string ........................................................... 29
Section 9.2: Use Right or Right$ to get the 3 right-most characters in a string ................................................... 29
Section 9.3: Use Mid or Mid$ to get specific characters from within a string ....................................................... 29
Section 9.4: Use Trim to get a copy of the string without any leading or trailing spaces .................................. 29
Chapter 10: Searching within strings for the presence of substrings ............................................. 30
Section 10.1: Use InStr to determine if a string contains a substring ..................................................................... 30
Section 10.2: Use InStrRev to find the position of the last instance of a substring .............................................. 30
Section 10.3: Use InStr to find the position of the first instance of a substring ..................................................... 30
Chapter 11: Assigning strings with repeated characters ........................................................................ 31
Section 11.1: Use the String function to assign a string with n repeated characters ............................................. 31
Section 11.2: Use the String and Space functions to assign an n-character string ............................................... 31
Chapter 12: Measuring the length of strings ................................................................................................ 32
Section 12.1: Use the Len function to determine the number of characters in a string ....................................... 32
Section 12.2: Use the LenB function to determine the number of bytes in a string ............................................. 32
Section 12.3: Prefer `If Len(myString) = 0 Then` over `If myString = "" Then` ......................................................... 32
Chapter 13: Converting other types to strings ............................................................................................ 33
Section 13.1: Use CStr to convert a numeric type to a string .................................................................................. 33
Section 13.2: Use Format to convert and format a numeric type as a string ....................................................... 33
Section 13.3: Use StrConv to convert a byte-array of single-byte characters to a string ................................... 33
Section 13.4: Implicitly convert a byte array of multi-byte-characters to a string ............................................... 33
Chapter 14: Date Time Manipulation ................................................................................................................ 34
Section 14.1: Calendar .................................................................................................................................................. 34
Section 14.2: Base functions ....................................................................................................................................... 34
Section 14.3: Extraction functions ............................................................................................................................... 36
Section 14.4: Calculation functions ............................................................................................................................. 37
Section 14.5: Conversion and Creation ...................................................................................................................... 39
Chapter 15: Data Types and Limits ................................................................................................................... 41
Section 15.1: Variant ..................................................................................................................................................... 41
Section 15.2: Boolean .................................................................................................................................................. 42
Section 15.3: String ....................................................................................................................................................... 42
Section 15.4: Byte ......................................................................................................................................................... 43
Section 15.5: Currency ................................................................................................................................................. 44
Section 15.6: Decimal ................................................................................................................................................... 44
Section 15.7: Integer .................................................................................................................................................... 44
Section 15.8: Long ........................................................................................................................................................ 44
Section 15.9: Single ...................................................................................................................................................... 45
Section 15.10: Double ................................................................................................................................................... 45
Section 15.11: Date ........................................................................................................................................................ 45
Section 15.12: LongLong .............................................................................................................................................. 46
Section 15.13: LongPtr .................................................................................................................................................. 46
Chapter 16: Naming Conventions ....................................................................................................................... 47
Section 16.1: Variable Names ...................................................................................................................................... 47
Section 16.2: Procedure Names ................................................................................................................................. 50
Chapter 17: Data Structures ................................................................................................................................. 52
Section 17.1: Linked List ............................................................................................................................................... 52
Section 17.2: Binary Tree ............................................................................................................................................. 53
Chapter 18: Arrays ...................................................................................................................................................... 54
Section 18.1: Multidimensional Arrays ........................................................................................................................ 54
Section 18.2: Dynamic Arrays (Array Resizing and Dynamic Handling) ............................................................... 59
Section 18.3: Jagged Arrays (Arrays of Arrays) ...................................................................................................... 60
Section 18.4: Declaring an Array in VBA ................................................................................................................... 63
Section 18.5: Use of Split to create an array from a string ..................................................................................... 64
Section 18.6: Iterating elements of an array ............................................................................................................. 65
Chapter 19: Copying, returning and passing arrays ................................................................................. 67
Section 19.1: Passing Arrays to Proceedures ............................................................................................................ 67
Section 19.2: Copying Arrays ...................................................................................................................................... 67
Section 19.3: Returning Arrays from Functions ........................................................................................................ 69
Chapter 20: Collections ............................................................................................................................................ 71
Section 20.1: Getting the Item Count of a Collection ............................................................................................... 71
Section 20.2: Determining if a Key or Item Exists in a Collection ........................................................................... 71
Section 20.3: Adding Items to a Collection ............................................................................................................... 72
Section 20.4: Removing Items From a Collection .................................................................................................... 73
Section 20.5: Retrieving Items From a Collection .................................................................................................... 74
Section 20.6: Clearing All Items From a Collection .................................................................................................. 75
Chapter 21: Operators .............................................................................................................................................. 77
Section 21.1: Concatenation Operators ..................................................................................................................... 77
Section 21.2: Comparison Operators ......................................................................................................................... 77
Section 21.3: Bitwise \ Logical Operators .................................................................................................................. 79
Section 21.4: Mathematical Operators ...................................................................................................................... 81
Chapter 22: Sorting .................................................................................................................................................... 82
Section 22.1: Algorithm Implementation - Quick Sort on a One-Dimensional Array ........................................... 82
Section 22.2: Using the Excel Library to Sort a One-Dimensional Array ............................................................... 82
Chapter 23: Flow control structures ................................................................................................................. 85
Section 23.1: For loop .................................................................................................................................................. 85
Section 23.2: Select Case ............................................................................................................................................ 86
Section 23.3: For Each loop ........................................................................................................................................ 87
Section 23.4: Do loop .................................................................................................................................................. 88
Section 23.5: While loop .............................................................................................................................................. 88
Chapter 24: Passing Arguments ByRef or ByVal ....................................................................................... 89
Section 24.1: Passing Simple Variables ByRef And ByVal ....................................................................................... 89
Section 24.2: ByRef ..................................................................................................................................................... 90
Section 24.3: ByVal ...................................................................................................................................................... 91
Chapter 25: Scripting.FileSystemObject ......................................................................................................... 93
Section 25.1: Retrieve only the path from a file path ............................................................................................... 93
Section 25.2: Retrieve just the extension from a file name .................................................................................... 93
Section 25.3: Recursively enumerate folders and files ........................................................................................... 93
Section 25.4: Strip file extension from a file name .................................................................................................. 94
Section 25.5: Enumerate files in a directory using FileSystemObject .................................................................... 94
Section 25.6: Creating a FileSystemObject ............................................................................................................... 95
Section 25.7: Reading a text file using a FileSystemObject .................................................................................... 95
Section 25.8: Creating a text file with FileSystemObject ......................................................................................... 96
Section 25.9: Using FSO.BuildPath to build a Full Path from folder path and file name ..................................... 96
Section 25.10: Writing to an existing file with FileSystemObject ............................................................................. 97
Chapter 26: Working With Files and Directories Without Using FileSystemObject .................. 98
Section 26.1: Determining If Folders and Files Exist ................................................................................................. 98
Section 26.2: Creating and Deleting File Folders ..................................................................................................... 99
Chapter 27: Reading 2GB+ files in binary in VBA and File Hashes .................................................. 100
Section 27.1: This have to be in a Class module, examples later referred as "Random" .................................. 100
Section 27.2: Code for Calculating File Hash in a Standard module ................................................................... 103
Section 27.3: Calculating all Files Hash from a root Folder .................................................................................. 105
Chapter 28: Creating a procedure ................................................................................................................... 109
Section 28.1: Introduction to procedures ................................................................................................................ 109
Section 28.2: Function With Examples .................................................................................................................... 109
Chapter 29: Procedure Calls ............................................................................................................................... 111
Section 29.1: This is confusing. Why not just always use parentheses? .............................................................. 111
Section 29.2: Implicit Call Syntax ............................................................................................................................. 111
Section 29.3: Optional Arguments ........................................................................................................................... 112
Section 29.4: Explicit Call Syntax ............................................................................................................................. 112
Section 29.5: Return Values ..................................................................................................................................... 113
Chapter 30: Conditional Compilation ............................................................................................................. 114
Section 30.1: Changing code behavior at compile time ........................................................................................ 114
Section 30.2: Using Declare Imports that work on all versions of Oce ............................................................ 115
Chapter 31: Object-Oriented VBA ..................................................................................................................... 117
Section 31.1: Abstraction ............................................................................................................................................ 117
Section 31.2: Encapsulation ...................................................................................................................................... 117
Section 31.3: Polymorphism ...................................................................................................................................... 121
Chapter 32: Creating a Custom Class ............................................................................................................. 124
Section 32.1: Adding a Property to a Class ............................................................................................................. 124
Section 32.2: Class module scope, instancing and re-use .................................................................................... 125
Section 32.3: Adding Functionality to a Class ........................................................................................................ 125
Chapter 33: Interfaces ........................................................................................................................................... 127
Section 33.1: Multiple Interfaces in One Class - Flyable and Swimable ............................................................... 127
Section 33.2: Simple Interface - Flyable .................................................................................................................. 128
Chapter 34: Recursion ........................................................................................................................................... 130
Section 34.1: Factorials .............................................................................................................................................. 130
Section 34.2: Folder Recursion ................................................................................................................................. 130
Chapter 35: Events ................................................................................................................................................... 132
Section 35.1: Sources and Handlers ......................................................................................................................... 132
Section 35.2: Passing data back to the event source ........................................................................................... 134
Chapter 36: Scripting.Dictionary object ........................................................................................................ 136
Section 36.1: Properties and Methods ..................................................................................................................... 136
Chapter 37: Working with ADO .......................................................................................................................... 138
Section 37.1: Making a connection to a data source ............................................................................................. 138
Section 37.2: Creating parameterized commands ................................................................................................ 138
Section 37.3: Retrieving records with a query ........................................................................................................ 139
Section 37.4: Executing non-scalar functions ......................................................................................................... 141
Chapter 38: Attributes ............................................................................................................................................ 142
Section 38.1: VB_PredeclaredId ............................................................................................................................... 142
Section 38.2: VB_[Var]UserMemId ......................................................................................................................... 142
Section 38.3: VB_Exposed ........................................................................................................................................ 143
Section 38.4: VB_Description ................................................................................................................................... 144
Section 38.5: VB_Name ............................................................................................................................................ 144
Section 38.6: VB_GlobalNameSpace ...................................................................................................................... 144
Section 38.7: VB_Createable ................................................................................................................................... 145
Chapter 39: User Forms ......................................................................................................................................... 146
Section 39.1: Best Practices ...................................................................................................................................... 146
Section 39.2: Handling QueryClose ......................................................................................................................... 148
Chapter 40: CreateObject vs. GetObject ..................................................................................................... 150
Section 40.1: Demonstrating GetObject and CreateObject .................................................................................. 150
Chapter 41: Non-Latin Characters ................................................................................................................... 151
Section 41.1: Non-Latin Text in VBA Code ............................................................................................................... 151
Section 41.2: Non-Latin Identifiers and Language Coverage ............................................................................... 152
Chapter 42: API Calls .............................................................................................................................................. 153
Section 42.1: Mac APIs ............................................................................................................................................... 153
Section 42.2: Get total monitors and screen resolution ........................................................................................ 153
Section 42.3: FTP and Regional APIs ....................................................................................................................... 154
Section 42.4: API declaration and usage ................................................................................................................ 157
Section 42.5: Windows API - Dedicated Module (1 of 2) ........................................................................................ 159
Section 42.6: Windows API - Dedicated Module (2 of 2) ....................................................................................... 163
Chapter 43: Automation or Using other applications Libraries ....................................................... 168
Section 43.1: VBScript Regular Expressions ............................................................................................................ 168
Section 43.2: Scripting File System Object ............................................................................................................. 169
Section 43.3: Scripting Dictionary object ................................................................................................................ 169
Section 43.4: Internet Explorer Object ..................................................................................................................... 170
Chapter 44: Macro security and signing of VBA-projects/-modules ........................................... 173
Section 44.1: Create a valid digital self-signed certificate SELFCERT.EXE .......................................................... 173
Chapter 45: VBA Run-Time Errors ................................................................................................................... 183
Section 45.1: Run-time error '6': Overflow ............................................................................................................... 183
Section 45.2: Run-time error '9': Subscript out of range ....................................................................................... 183
Section 45.3: Run-time error '13': Type mismatch .................................................................................................. 184
Section 45.4: Run-time error '91': Object variable or With block variable not set .............................................. 184
Section 45.5: Run-time error '20': Resume without error ...................................................................................... 185
Section 45.6: Run-time error '3': Return without GoSub ........................................................................................ 186
Chapter 46: Error Handling ................................................................................................................................. 188
Section 46.1: Avoiding error conditions ................................................................................................................... 188
Section 46.2: Custom Errors ..................................................................................................................................... 188
Section 46.3: Resume keyword ................................................................................................................................ 189
Section 46.4: On Error statement ............................................................................................................................ 191
Credits ............................................................................................................................................................................ 194
You may also like ...................................................................................................................................................... 196
GoalKicker.com – VBA Notes for Professionals 1
About
Please feel free to share this PDF with anyone for free,
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https://goalkicker.com/VBABook
This VBA Notes for Professionals book is compiled from Stack Overflow
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GoalKicker.com – VBA Notes for Professionals 2
Chapter 1: Getting started with VBA
Version Office Versions Release Date Notes Release Date
Vba6 ? - 2007 [Sometime after][1] 1992-06-30
Vba7 2010 - 2016 [blog.techkit.com][2] 2010-04-15
VBA for Mac 2004, 2011 - 2016 2004-05-11
Section 1.1: Accessing the Visual Basic Editor in Microsoft
Oce
You can open the VB editor in any of the Microsoft Office applications by pressing Alt + F11 or going to the
Developer tab and clicking on the "Visual Basic" button. If you don't see the Developer tab in the Ribbon, check if
this is enabled.
By default the Developer tab is disabled. To enable the Developer tab go to File -> Options, select Customize Ribbon
in the list on the left. In the right "Customize the Ribbon" treeview find the Developer tree item and set the check
for the Developer checkbox to checked. Click Ok to close the Options dialog.
The Developer tab is now visible in the Ribbon on which you can click on "Visual Basic" to open the Visual Basic
Editor. Alternatively you can click on "View Code" to directly view the code pane of the currently active element, e.g.
WorkSheet, Chart, Shape.
GoalKicker.com – VBA Notes for Professionals 3
You can use VBA to automate almost any action that can be performed interactively (manually) and also provide
functionality that is not available in Microsoft Office. VBA can create a document, add text to it, format it, edit it, and
save it, all without human intervention.
Section 1.2: Debugging
Debugging is a very powerful way to have a closer look and fix incorrectly working (or non working) code.
Run code step by step
First thing you need to do during debugging is to stop the code at specific locations and then run it line by line to
see whether that happens what's expected.
Breakpoint ( F9 , Debug - Toggle breakpoint): You can add a breakpoint to any executed line (e.g. not to
declarations), when execution reaches that point it stops, and gives control to user.
You can also add the Stop keyword to a blank line to have the code stop at that location on runtime. This is
useful if, for example, before declaration lines to which you can't add a breakpoint with F9
Step into ( F8 , Debug - Step into): executes only one line of code, if that's a call of a user defined sub /
function, then that's executed line by line.
Step over ( Shift + F8 , Debug - Step over): executes one line of code, doesn't enter user defined subs /
functions.
Step out ( Ctrl + Shift + F8 , Debug - Step out): Exit current sub / function (run code until its end).
GoalKicker.com – VBA Notes for Professionals 4
Run to cursor ( Ctrl + F8 , Debug - Run to cursor): run code until reaching the line with the cursor.
You can use Debug.Print to print lines to the Immediate Window at runtime. You may also use Debug.? as a
shortcut for Debug.Print
Watches window
Running code line by line is only the first step, we need to know more details and one tool for that is the watch
window (View - Watch window), here you can see values of defined expressions. To add a variable to the watch
window, either:
Right-click on it then select "Add watch".
Right-click in watch window, select "Add watch".
Go to Debug - Add watch.
When you add a new expression you can choose whether you just want to see it's value, or also break code
execution when it's true or when its value changes.
Immediate Window
The immediate window allows you to execute arbitrary code or print items by preceeding them with either the
Print keyword or a single question mark "?"
Some examples:
? ActiveSheet.Name - returns name of the active sheet
Print ActiveSheet.Name - returns the name of the active sheet
? foo - returns the value of foo*
x = 10 sets x to 10*
* Getting/Setting values for variables via the Immediate Window can only be done during runtime
Debugging best practices
Whenever your code doesn't work as expected first thing you should do is to read it again carefully, looking for
mistakes.
If that doesn't help, then start debugging it; for short procedures it can be efficient to just execute it line by line, for
longer ones you probably need to set breakpoints or breaks on watched expressions, the goal here is to find the
line not working as expected.
Once you have the line which gives the incorrect result, but the reason is not yet clear, try to simplify expressions,
or replace variables with constants, that can help understanding whether variables' value are wrong.
If you still can't solve it, and ask for help:
Include as small part of your code as possible for understanding of your problem
If the problem is not related to the value of variables, then replace them by constants. (so, instead of
Sheets(a*b*c+d^2).Range(addressOfRange) write Sheets(4).Range("A2"))
Describe which line gives the wrong behaviour, and what it is (error, wrong result...)
Section 1.3: First Module and Hello World
To start coding in the first place, you have to right click your VBA Project in the left list and add a new Module. Your
first Hello-World Code could look like this:
GoalKicker.com – VBA Notes for Professionals 5
Sub HelloWorld()
MsgBox "Hello, World!"
End Sub
To test it, hit the Play-Button in your Toolbar or simply hit the F5 key. Congratulations! You've built your first own
VBA Module.
GoalKicker.com – VBA Notes for Professionals 6
Chapter 2: Comments
Section 2.1: Apostrophe Comments
A comment is marked by an apostrophe ('), and ignored when the code executes. Comments help explain your
code to future readers, including yourself.
Since all lines starting with a comment are ignored, they can also be used to prevent code from executing (while
you debug or refactor). Placing an apostrophe ' before your code turns it into a comment. (This is called
commenting out the line.)
Sub InlineDocumentation()
'Comments start with an "'"
'They can be place before a line of code, which prevents the line from executing
'Debug.Print "Hello World"
'They can also be placed after a statement
'The statement still executes, until the compiler arrives at the comment
Debug.Print "Hello World" 'Prints a welcome message
'Comments can have 0 indention....
'... or as much as needed
'''' Comments can contain multiple apostrophes ''''
'Comments can span lines (using line continuations) _
but this can make for hard to read code
'If you need to have mult-line comments, it is often easier to
'use an apostrophe on each line
'The continued statement syntax (:) is treated as part of the comment, so
'it is not possible to place an executable statement after a comment
'This won't run : Debug.Print "Hello World"
End Sub
'Comments can appear inside or outside a procedure
Section 2.2: REM Comments
Sub RemComments()
Rem Comments start with "Rem" (VBA will change any alternate casing to "Rem")
Rem is an abbreviation of Remark, and similar to DOS syntax
Rem Is a legacy approach to adding comments, and apostrophes should be preferred
Rem Comments CANNOT appear after a statement, use the apostrophe syntax instead
Rem Unless they are preceded by the instruction separator token
Debug.Print "Hello World": Rem prints a welcome message
Debug.Print "Hello World" 'Prints a welcome message
'Rem cannot be immediately followed by the following characters "!,@,#,$,%,&"
'Whereas the apostrophe syntax can be followed by any printable character.
End Sub
Rem Comments can appear inside or outside a procedure
GoalKicker.com – VBA Notes for Professionals 7
Chapter 3: String Literals - Escaping, nonprintable
characters and linecontinuations
Section 3.1: Escaping the " character
VBA syntax requires that a string-literal appear within " marks, so when your string needs to contain quotation
marks, you'll need to escape/prepend the " character with an extra " so that VBA understands that you intend the
"" to be interpreted as a " string.
'The following 2 lines produce the same output
Debug.Print "The man said, ""Never use air-quotes"""
Debug.Print "The man said, " & """" & "Never use air-quotes" & """"
'Output:
'The man said, "Never use air-quotes"
'The man said, "Never use air-quotes"
Section 3.2: Assigning long string literals
The VBA editor only allows 1023 characters per line, but typically only the first 100-150 characters are visible
without scrolling. If you need to assign long string literals, but you want to keep your code readable, you'll need to
use line-continuations and concatenation to assign your string.
Debug.Print "Lorem ipsum dolor sit amet, consectetur adipiscing elit. " & _
"Integer hendrerit maximus arcu, ut elementum odio varius " & _
"nec. Integer ipsum enim, iaculis et egestas ac, condiment" & _
"um ut tellus."
'Output:
'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer hendrerit maximus arcu, ut
elementum odio varius nec. Integer ipsum enim, iaculis et egestas ac, condimentum ut tellus.
VBA will let you use a limited number of line-continuations (the actual number varies by the length of each line
within the continued-block), so if you have very long strings, you'll need to assign and re-assign with concatenation.
Dim loremIpsum As String
'Assign the first part of the string
loremIpsum = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. " & _
"Integer hendrerit maximus arcu, ut elementum odio varius "
'Re-assign with the previous value AND the next section of the string
loremIpsum = loremIpsum & _
"nec. Integer ipsum enim, iaculis et egestas ac, condiment" & _
"um ut tellus."
Debug.Print loremIpsum
'Output:
'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer hendrerit maximus arcu, ut
elementum odio varius nec. Integer ipsum enim, iaculis et egestas ac, condimentum ut tellus.
Section 3.3: Using VBA string constants
VBA defines a number of string constants for special characters like:
GoalKicker.com – VBA Notes for Professionals 8
vbCr : Carriage-Return 'Same as "\r" in C style languages.
vbLf : Line-Feed 'Same as "\n" in C style languages.
vbCrLf : Carriage-Return & Line-Feed (a new-line in Windows)
vbTab: Tab Character
vbNullString: an empty string, like ""
You can use these constants with concatenation and other string functions to build string-literals with specialcharacters.
Debug.Print "Hello " & vbCrLf & "World"
'Output:
'Hello
'World
Debug.Print vbTab & "Hello" & vbTab & "World"
'Output:
' Hello World
Dim EmptyString As String
EmptyString = vbNullString
Debug.Print EmptyString = ""
'Output:
'True
Using vbNullString is considered better practice than the equivalent value of "" due to differences in how the
code is compiled. Strings are accessed via a pointer to an allocated area of memory, and the VBA compiler is smart
enough to use a null pointer to represent vbNullString. The literal "" is allocated memory as if it were a String
typed Variant, making the use of the constant much more efficient:
Debug.Print StrPtr(vbNullString) 'Prints 0.
Debug.Print StrPtr("") 'Prints a memory address.
GoalKicker.com – VBA Notes for Professionals 9
Chapter 4: VBA Option Keyword
Option Detail
Explicit Require variable declaration in the module it's specified in (ideally all of them); with this option
specified, using an undeclared (/mispelled) variable becomes a compilation error.
Compare Text Makes the module's string comparisons be case-insensitive, based on system locale,
prioritizing alphabetical equivalency (e.g. "a" = "A").
Compare Binary
Default string comparison mode. Makes the module's string comparisons be case sensitive,
comparing strings using the binary representation / numeric value of each character (e.g.
ASCII).
Compare Database (MS-Access only) Makes the module's string comparisons work the way they would in an SQL
statement.
Private Module
Prevents the module's Public member from being accessed from outside of the project that
the module resides in, effectively hiding procedures from the host application (i.e. not available
to use as macros or user-defined functions).
Option Base 0 Default setting. Sets the implicit array lower bound to 0 in a module. When an array is declared
without an explicit lower boundary value, 0 will be used.
Option Base 1 Sets the implicit array lower bound to 1 in a module. When an array is declared without an
explicit lower boundary value, 1 will be used.
Section 4.1: Option Explicit
It is deemed best practice to always use Option Explicit in VBA as it forces the developer to declare all their
variables before use. This has other benefits too, such as auto-capitalization for declared variable names and
IntelliSense.
Option Explicit
Sub OptionExplicit()
Dim a As Integer
a = 5
b = 10 '// Causes compile error as 'b' is not declared
End Sub
Setting Require Variable Declaration within the VBE's Tools ► Options ► Editor property page will put the Option
Explicit statement at the top of each newly created code sheet.
GoalKicker.com – VBA Notes for Professionals 10
This will avoid silly coding mistakes like misspellings as well as influencing you to use the correct variable type in the
variable declaration. (Some more examples are given at ALWAYS Use "Option Explicit".)
Section 4.2: Option Base {0 | 1}
Option Base is used to declare the default lower bound of array elements. It is declared at module level and is
valid only for the current module.
By default (and thus if no Option Base is specified), the Base is 0. Which means that the first element of any array
declared in the module has an index of 0.
If Option Base 1 is specified, the first array element has the index 1
Example in Base 0 :
Option Base 0
Sub BaseZero()
Dim myStrings As Variant
' Create an array out of the Variant, having 3 fruits elements
myStrings = Array("Apple", "Orange", "Peach")
Debug.Print LBound(myStrings) ' This Prints "0"
Debug.Print UBound(myStrings) ' This print "2", because we have 3 elements beginning at 0 ->
0,1,2
For i = 0 To UBound(myStrings)
Debug.Print myStrings(i) ' This will print "Apple", then "Orange", then "Peach"
Next i
End Sub
Same Example with Base 1
Option Base 1
GoalKicker.com – VBA Notes for Professionals 11
Sub BaseOne()
Dim myStrings As Variant
' Create an array out of the Variant, having 3 fruits elements
myStrings = Array("Apple", "Orange", "Peach")
Debug.Print LBound(myStrings) ' This Prints "1"
Debug.Print UBound(myStrings) ' This print "3", because we have 3 elements beginning at 1 ->
1,2,3
For i = 0 To UBound(myStrings)
Debug.Print myStrings(i) ' This triggers an error 9 "Subscript out of range"
Next i
End Sub
The second example generated a Subscript out of range (Error 9) at the first loop stage because an attempt to
access the index 0 of the array was made, and this index doesn't exists as the module is declared with Base 1
The correct code with Base 1 is :
For i = 1 To UBound(myStrings)
Debug.Print myStrings(i) ' This will print "Apple", then "Orange", then "Peach"
Next i
It should be noted that the Split function always creates an array with a zero-based element index regardless of
any Option Base setting. Examples on how to use the Split function can be found here
Split Function
Returns a zero-based, one-dimensional array containing a specified number of substrings.
In Excel, the Range.Value and Range.Formula properties for a multi-celled range always returns a 1-based 2D
Variant array.
Likewise, in ADO, the Recordset.GetRows method always returns a 1-based 2D array.
One recommended 'best practice' is to always use the LBound and UBound functions to determine the extents of
an array.
'for single dimensioned array
Debug.Print LBound(arr) & ":" & UBound(arr)
Dim i As Long
For i = LBound(arr) To UBound(arr)
Debug.Print arr(i)
Next i
'for two dimensioned array
Debug.Print LBound(arr, 1) & ":" & UBound(arr, 1)
Debug.Print LBound(arr, 2) & ":" & UBound(arr, 2)
Dim i As long, j As Long
For i = LBound(arr, 1) To UBound(arr, 1)
For j = LBound(arr, 2) To UBound(arr, 2)
Debug.Print arr(i, j)
Next j
GoalKicker.com – VBA Notes for Professionals 12
Next i
The Option Base 1 must be at the top of every code module where an array is created or re-dimensioned if arrays
are to be consistently created with an lower boundary of 1.
Section 4.3: Option Compare {Binary | Text | Database}
Option Compare Binary
Binary comparison makes all checks for string equality within a module/class case sensitive. Technically, with this
option, string comparisons are performed using sort order of the binary representations of each character.
A < B < E < Z < a < b < e < z
If no Option Compare is specified in a module, Binary is used by default.
Option Compare Binary
Sub CompareBinary()
Dim foo As String
Dim bar As String
'// Case sensitive
foo = "abc"
bar = "ABC"
Debug.Print (foo = bar) '// Prints "False"
'// Still differentiates accented characters
foo = "ábc"
bar = "abc"
Debug.Print (foo = bar) '// Prints "False"
'// "b" (Chr 98) is greater than "a" (Chr 97)
foo = "a"
bar = "b"
Debug.Print (bar > foo) '// Prints "True"
'// "b" (Chr 98) is NOT greater than "á" (Chr 225)
foo = "á"
bar = "b"
Debug.Print (bar > foo) '// Prints "False"
End Sub
Option Compare Text
Option Compare Text makes all string comparisons within a module/class use a case insensitive comparison.
(A | a) < (B | b) < (Z | z)
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Option Compare Text
Sub CompareText()
Dim foo As String
Dim bar As String
'// Case insensitivity
foo = "abc"
bar = "ABC"
Debug.Print (foo = bar) '// Prints "True"
'// Still differentiates accented characters
foo = "ábc"
bar = "abc"
Debug.Print (foo = bar) '// Prints "False"
'// "b" still comes after "a" or "á"
foo = "á"
bar = "b"
Debug.Print (bar > foo) '// Prints "True"
End Sub
Option Compare Database
Option Compare Database is only available within MS Access. It sets the module/class to use the current database
settings to determine whether to use Text or Binary mode.
Note: The use of this setting is discouraged unless the module is used for writing custom Access UDFs (User defined
functions) that should treat text comparisons in the same manner as SQL queries in that database.
GoalKicker.com – VBA Notes for Professionals 14
Chapter 5: Declaring Variables
Section 5.1: Type Hints
Type Hints are heavily discouraged. They exist and are documented here for historical and backward-compatibility
reasons. You should use the As [DataType] syntax instead.
Public Sub ExampleDeclaration()
Dim someInteger% '% Equivalent to "As Integer"
Dim someLong& '& Equivalent to "As Long"
Dim someDecimal@ '@ Equivalent to "As Currency"
Dim someSingle! '! Equivalent to "As Single"
Dim someDouble# '# Equivalent to "As Double"
Dim someString$ '$ Equivalent to "As String"
Dim someLongLong^ '^ Equivalent to "As LongLong" in 64-bit VBA hosts
End Sub
Type hints significantly decrease code readability and encourage a legacy Hungarian Notation which also hinders
readability:
Dim strFile$
Dim iFile%
Instead, declare variables closer to their usage and name things for what they're used, not after their type:
Dim path As String
Dim handle As Integer
Type hints can also be used on literals, to enforce a specific type. By default, a numeric literal smaller than 32,768
will be interpreted as an Integer literal, but with a type hint you can control that:
Dim foo 'implicit Variant
foo = 42& ' foo is now a Long
foo = 42# ' foo is now a Double
Debug.Print TypeName(42!) ' prints "Single"
Type hints are usually not needed on literals, because they would be assigned to a variable declared with an explicit
type, or implicitly converted to the appropriate type when passed as parameters. Implicit conversions can be
avoided using one of the explicit type conversion functions:
'Calls procedure DoSomething and passes a literal 42 as a Long using a type hint
DoSomething 42&
'Calls procedure DoSomething and passes a literal 42 explicitly converted to a Long
DoSomething CLng(42)
String-returning built-in functions
The majority of the built-in functions that handle strings come in two versions: A loosely typed version that returns
a Variant, and a strongly typed version (ending with $) that returns a String. Unless you are assigning the return
value to a Variant, you should prefer the version that returns a String - otherwise there is an implicit conversion of
the return value.
GoalKicker.com – VBA Notes for Professionals 15
Debug.Print Left(foo, 2) 'Left returns a Variant
Debug.Print Left$(foo, 2) 'Left$ returns a String
These functions are:
VBA.Conversion.Error -> VBA.Conversion.Error$
VBA.Conversion.Hex -> VBA.Conversion.Hex$
VBA.Conversion.Oct -> VBA.Conversion.Oct$
VBA.Conversion.Str -> VBA.Conversion.Str$
VBA.FileSystem.CurDir -> VBA.FileSystem.CurDir$
VBA.[_HiddenModule].Input -> VBA.[_HiddenModule].Input$
VBA.[_HiddenModule].InputB -> VBA.[_HiddenModule].InputB$
VBA.Interaction.Command -> VBA.Interaction.Command$
VBA.Interaction.Environ -> VBA.Interaction.Environ$
VBA.Strings.Chr -> VBA.Strings.Chr$
VBA.Strings.ChrB -> VBA.Strings.ChrB$
VBA.Strings.ChrW -> VBA.Strings.ChrW$
VBA.Strings.Format -> VBA.Strings.Format$
VBA.Strings.LCase -> VBA.Strings.LCase$
VBA.Strings.Left -> VBA.Strings.Left$
VBA.Strings.LeftB -> VBA.Strings.LeftB$
VBA.Strings.LTtrim -> VBA.Strings.LTrim$
VBA.Strings.Mid -> VBA.Strings.Mid$
VBA.Strings.MidB -> VBA.Strings.MidB$
VBA.Strings.Right -> VBA.Strings.Right$
VBA.Strings.RightB -> VBA.Strings.RightB$
VBA.Strings.RTrim -> VBA.Strings.RTrim$
VBA.Strings.Space -> VBA.Strings.Space$
VBA.Strings.Str -> VBA.Strings.Str$
VBA.Strings.String -> VBA.Strings.String$
VBA.Strings.Trim -> VBA.Strings.Trim$
VBA.Strings.UCase -> VBA.Strings.UCase$
Note that these are function aliases, not quite type hints. The Left function corresponds to the hidden B_Var_Left
function, while the Left$ version corresponds to the hidden B_Str_Left function.
In very early versions of VBA the $ sign isn't an allowed character and the function name had to be enclosed in
square brackets. In Word Basic, there were many, many more functions that returned strings that ended in $.
Section 5.2: Variables
Scope
A variable can be declared (in increasing visibility level):
At procedure level, using the Dim keyword in any procedure; a local variable.
At module level, using the Private keyword in any type of module; a private field.
At instance level, using the Friend keyword in any type of class module; a friend field.
At instance level, using the Public keyword in any type of class module; a public field.
Globally, using the Public keyword in a standard module; a global variable.
Variables should always be declared with the smallest possible scope: prefer passing parameters to procedures,
rather than declaring global variables.
GoalKicker.com – VBA Notes for Professionals 16
See Access Modifiers for more information.
Local variables
Use the Dim keyword to declare a local variable:
Dim identifierName [As Type][, identifierName [As Type], ...]
The [As Type] part of the declaration syntax is optional. When specified, it sets the variable's data type, which
determines how much memory will be allocated to that variable. This declares a String variable:
Dim identifierName As String
When a type is not specified, the type is implicitly Variant:
Dim identifierName 'As Variant is implicit
The VBA syntax also supports declaring multiple variables in a single statement:
Dim someString As String, someVariant, someValue As Long
Notice that the [As Type] has to be specified for each variable (other than 'Variant' ones). This is a relatively
common trap:
Dim integer1, integer2, integer3 As Integer 'Only integer3 is an Integer.
'The rest are Variant.
Static variables
Local variables can also be Static. In VBA the Static keyword is used to make a variable "remember" the value it
had, last time a procedure was called:
Private Sub DoSomething()
Static values As Collection
If values Is Nothing Then
Set values = New Collection
values.Add "foo"
values.Add "bar"
End If
DoSomethingElse values
End Sub
Here the values collection is declared as a Static local; because it's an object variable, it is initialized to Nothing.
The condition that follows the declaration verifies if the object reference was Set before - if it's the first time the
procedure runs, the collection gets initialized. DoSomethingElse might be adding or removing items, and they'll still
be in the collection next time DoSomething is called.
Alternative
VBA's Static keyword can easily be misunderstood - especially by seasoned programmers that usually
work in other languages. In many languages, static is used to make a class member (field, property,
method, ...) belong to the type rather than to the instance. Code in static context cannot reference code
in instance context. The VBA Static keyword means something wildly different.
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Often, a Static local could just as well be implemented as a Private, module-level variable (field) - however this
challenges the principle by which a variable should be declared with the smallest possible scope; trust your
instincts, use whichever you prefer - both will work... but using Static without understanding what it does could
lead to interesting bugs.
Dim vs. Private
The Dim keyword is legal at procedure and module levels; its usage at module level is equivalent to using the
Private keyword:
Option Explicit
Dim privateField1 As Long 'same as Private privateField2 as Long
Private privateField2 As Long 'same as Dim privateField2 as Long
The Private keyword is only legal at module level; this invites reserving Dim for local variables and declaring
module variables with Private, especially with the contrasting Public keyword that would have to be used anyway
to declare a public member. Alternatively use Dim everywhere - what matters is consistency:
"Private fields"
DO use Private to declare a module-level variable.
DO use Dim to declare a local variable.
DO NOT use Dim to declare a module-level variable.
"Dim everywhere"
DO use Dim to declare anything private/local.
DO NOT use Private to declare a module-level variable.
AVOID declaring Public fields.*
*In general, one should avoid declaring Public or Global fields anyway.
Fields
A variable declared at module level, in the declarations section at the top of the module body, is a field. A Public field
declared in a standard module is a global variable:
Public PublicField As Long
A variable with a global scope can be accessed from anywhere, including other VBA projects that would reference
the project it's declared in.
To make a variable global/public, but only visible from within the project, use the Friend modifier:
Friend FriendField As Long
This is especially useful in add-ins, where the intent is that other VBA projects reference the add-in project and can
consume the public API.
Friend FriendField As Long 'public within the project, aka for "friend" code
Public PublicField As Long 'public within and beyond the project
Friend fields are not available in standard modules.
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Instance Fields
A variable declared at module level, in the declarations section at the top of the body of a class module (including
ThisWorkbook, ThisDocument, Worksheet, UserForm and class modules), is an instance field: it only exists as long as
there's an instance of the class around.
'> Class1
Option Explicit
Public PublicField As Long
'> Module1
Option Explicit
Public Sub DoSomething()
'Class1.PublicField means nothing here
With New Class1
.PublicField = 42
End With
'Class1.PublicField means nothing here
End Sub
Encapsulating fields
Instance data is often kept Private, and dubbed encapsulated. A private field can be exposed using a Property
procedure. To expose a private variable publicly without giving write access to the caller, a class module (or a
standard module) implements a Property Get member:
Option Explicit
Private encapsulated As Long
Public Property Get SomeValue() As Long
SomeValue = encapsulated
End Property
Public Sub DoSomething()
encapsulated = 42
End Sub
The class itself can modify the encapsulated value, but the calling code can only access the Public members (and
Friend members, if the caller is in the same project).
To allow the caller to modify:
An encapsulated value, a module exposes a Property Let member.
An encapsulated object reference, a module exposes a Property Set member.
Section 5.3: Constants (Const)
If you have a value that never changes in your application, you can define a named constant and use it in place of a
literal value.
You can use Const only at module or procedure level. This means the declaration context for a variable must be a
class, structure, module, procedure, or block, and cannot be a source file, namespace, or interface.
Public Const GLOBAL_CONSTANT As String = "Project Version #1.000.000.001"
Private Const MODULE_CONSTANT As String = "Something relevant to this Module"
Public Sub ExampleDeclaration()
GoalKicker.com – VBA Notes for Professionals 19
Const SOME_CONSTANT As String = "Hello World"
Const PI As Double = 3.141592653
End Sub
Whilst it can be considered good practice to specify Constant types, it isn't strictly required. Not specifying the type
will still result in the correct type:
Public Const GLOBAL_CONSTANT = "Project Version #1.000.000.001" 'Still a string
Public Sub ExampleDeclaration()
Const SOME_CONSTANT = "Hello World" 'Still a string
Const DERIVED_CONSTANT = SOME_CONSTANT 'DERIVED_CONSTANT is also a string
Const VAR_CONSTANT As Variant = SOME_CONSTANT 'VAR_CONSTANT is Variant/String
Const PI = 3.141592653 'Still a double
Const DERIVED_PI = PI 'DERIVED_PI is also a double
Const VAR_PI As Variant = PI 'VAR_PI is Variant/Double
End Sub
Note that this is specific to Constants and in contrast to variables where not specifying the type results in a Variant
type.
While it is possible to explicitly declare a constant as a String, it is not possible to declare a constant as a string using
fixed-width string syntax
'This is a valid 5 character string constant
Const FOO As String = "ABCDE"
'This is not valid syntax for a 5 character string constant
Const FOO As String * 5 = "ABCDE"
Section 5.4: Declaring Fixed-Length Strings
In VBA, Strings can be declared with a specific length; they are automatically padded or truncated to maintain that
length as declared.
Public Sub TwoTypesOfStrings()
Dim FixedLengthString As String * 5 ' declares a string of 5 characters
Dim NormalString As String
Debug.Print FixedLengthString ' Prints " "
Debug.Print NormalString ' Prints ""
FixedLengthString = "123" ' FixedLengthString now equals "123 "
NormalString = "456" ' NormalString now equals "456"
FixedLengthString = "123456" ' FixedLengthString now equals "12345"
NormalString = "456789" ' NormalString now equals "456789"
End Sub
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Section 5.5: When to use a Static variable
A Static variable declared locally is not destructed and does not lose its value when the Sub procedure is exited.
Subsequent calls to the procedure do not require re-initialization or assignment although you may want to 'zero'
any remembered value(s).
These are particularly useful when late binding an object in a 'helper' sub that is called repeatedly.
Snippet 1: Reuse a Scripting.Dictionary object across many worksheets
Option Explicit
Sub main()
Dim w As Long
For w = 1 To Worksheets.Count
processDictionary ws:=Worksheets(w)
Next w
End Sub
Sub processDictionary(ws As Worksheet)
Dim i As Long, rng As Range
Static dict As Object
If dict Is Nothing Then
'initialize and set the dictionary object
Set dict = CreateObject("Scripting.Dictionary")
dict.CompareMode = vbTextCompare
Else
'remove all pre-existing dictionary entries
' this may or may not be desired if a single dictionary of entries
' from all worksheets is preferred
dict.RemoveAll
End If
With ws
'work with a fresh dictionary object for each worksheet
' without constructing/destructing a new object each time
' or do not clear the dictionary upon subsequent uses and
' build a dictionary containing entries from all worksheets
End With
End Sub
Snippet 2: Create a worksheet UDF that late binds the VBScript.RegExp object
Option Explicit
Function numbersOnly(str As String, _
Optional delim As String = ", ")
Dim n As Long, nums() As Variant
Static rgx As Object, cmat As Object
'with rgx as static, it only has to be created once
'this is beneficial when filling a long column with this UDF
If rgx Is Nothing Then
Set rgx = CreateObject("VBScript.RegExp")
Else
Set cmat = Nothing
GoalKicker.com – VBA Notes for Professionals 21
End If
With rgx
.Global = True
.MultiLine = True
.Pattern = "[0-9]{1,999}"
If .Test(str) Then
Set cmat = .Execute(str)
'resize the nums array to accept the matches
ReDim nums(cmat.Count - 1)
'populate the nums array with the matches
For n = LBound(nums) To UBound(nums)
nums(n) = cmat.Item(n)
Next n
'convert the nums array to a delimited string
numbersOnly = Join(nums, delim)
Else
numbersOnly = vbNullString
End If
End With
End Function
Example of UDF with Static object filled through a half-million rows
*Elapsed times to fill 500K rows with UDF:
- with Dim rgx As Object: 148.74 seconds
- with Static rgx As Object: 26.07 seconds
* These should be considered for relative comparison only. Your own results will vary according to the
complexity and
scope of the operations performed.
Remember that a UDF is not calculated once in the lifetime of a workbook. Even a non-volatile UDF will recalculate
whenever the values within the range(s) it references are subject to change. Each subsequent recalculation event
only increases the benefits of a statically declared variable.
A Static variable is available for the lifetime of the module, not the procedure or function in which it was
declared and assigned.
Static variables can only be declared locally.
Static variable hold many of the same properties of a private module level variable but with a more restricted
scope.
Related reference: Static (Visual Basic)
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Section 5.6: Implicit And Explicit Declaration
If a code module does not contain Option Explicit at the top of the module, then the compiler will automatically
(that is, "implicitly") create variables for you when you use them. They will default to variable type Variant.
Public Sub ExampleDeclaration()
someVariable = 10 '
someOtherVariable = "Hello World"
'Both of these variables are of the Variant type.
End Sub
In the above code, if Option Explicit is specified, the code will interrupt because it is missing the required Dim
statements for someVariable and someOtherVariable.
Option Explicit
Public Sub ExampleDeclaration()
Dim someVariable As Long
someVariable = 10
Dim someOtherVariable As String
someOtherVariable = "Hello World"
End Sub
It is considered best practice to use Option Explicit in code modules, to ensure that you declare all variables.
See VBA Best Practices how to set this option by default.
Section 5.7: Access Modifiers
The Dim statement should be reserved for local variables. At module-level, prefer explicit access modifiers:
Private for private fields, which can only be accessed within the module they're declared in.
Public for public fields and global variables, which can be accessed by any calling code.
Friend for variables public within the project, but inaccessible to other referencing VBA projects (relevant for
add-ins)
Global can also be used for Public fields in standard modules, but is illegal in class modules and is obsolete
anyway - prefer the Public modifier instead. This modifier isn't legal for procedures either.
Access modifiers are applicable to variables and procedures alike.
Private ModuleVariable As String
Public GlobalVariable As String
Private Sub ModuleProcedure()
ModuleVariable = "This can only be done from within the same Module"
End Sub
Public Sub GlobalProcedure()
GlobalVariable = "This can be done from any Module within this Project"
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End Sub
Option Private Module
Public parameterless Sub procedures in standard modules are exposed as macros and can be attached to controls
and keyboard shortcuts in the host document.
Conversely, public Function procedures in standard modules are exposed as user-defined functions (UDF's) in the
host application.
Specifying Option Private Module at the top of a standard module prevents its members from being exposed as
macros and UDF's to the host application.
GoalKicker.com – VBA Notes for Professionals 24
Chapter 6: Declaring and assigning strings
Section 6.1: Assignment to and from a byte array
Strings can be assigned directly to byte arrays and visa-versa. Remember that Strings are stored in a Multi-Byte
Character Set (see Remarks below) so only every other index of the resulting array will be the portion of the
character that falls within the ASCII range.
Dim bytes() As Byte
Dim example As String
example = "Testing."
bytes = example 'Direct assignment.
'Loop through the characters. Step 2 is used due to wide encoding.
Dim i As Long
For i = LBound(bytes) To UBound(bytes) Step 2
Debug.Print Chr$(bytes(i)) 'Prints T, e, s, t, i, n, g, .
Next
Dim reverted As String
reverted = bytes 'Direct assignment.
Debug.Print reverted 'Prints "Testing."
Section 6.2: Declare a string constant
Const appName As String = "The App For That"
Section 6.3: Declare a variable-width string variable
Dim surname As String 'surname can accept strings of variable length
surname = "Smith"
surname = "Johnson"
Section 6.4: Declare and assign a fixed-width string
'Declare and assign a 1-character fixed-width string
Dim middleInitial As String * 1 'middleInitial must be 1 character in length
middleInitial = "M"
'Declare and assign a 2-character fixed-width string `stateCode`,
'must be 2 characters in length
Dim stateCode As String * 2
stateCode = "TX"
Section 6.5: Declare and assign a string array
'Declare, dimension and assign a string array with 3 elements
Dim departments(2) As String
departments(0) = "Engineering"
departments(1) = "Finance"
departments(2) = "Marketing"
'Declare an undimensioned string array and then dynamically assign with
'the results of a function that returns a string array
GoalKicker.com – VBA Notes for Professionals 25
Dim stateNames() As String
stateNames = VBA.Strings.Split("Texas;California;New York", ";")
'Declare, dimension and assign a fixed-width string array
Dim stateCodes(2) As String * 2
stateCodes(0) = "TX"
stateCodes(1) = "CA"
stateCodes(2) = "NY"
Section 6.6: Assign specific characters within a string using
Mid statement
VBA offers a Mid function for returning substrings within a string, but it also offers the Mid Statement which can be
used to assign substrings or individual characters withing a string.
The Mid function will typically appear on the right-hand-side of an assignment statement or in a condition, but the
Mid Statement typically appears on the left hand side of an assignment statement.
Dim surname As String
surname = "Smith"
'Use the Mid statement to change the 3rd character in a string
Mid(surname, 3, 1) = "y"
Debug.Print surname
'Output:
'Smyth
Note: If you need to assign to individual bytes in a string instead of individual characters within a string (see the
Remarks below regarding the Multi-Byte Character Set), the MidB statement can be used. In this instance, the
second argument for the MidB statement is the 1-based position of the byte where the replacement will start so the
equivalent line to the example above would be MidB(surname, 5, 2) = "y".
GoalKicker.com – VBA Notes for Professionals 26
Chapter 7: Concatenating strings
Section 7.1: Concatenate an array of strings using the Join
function
'Declare and assign a string array
Dim widgetNames(2) As String
widgetNames(0) = "foo"
widgetNames(1) = "bar"
widgetNames(2) = "fizz"
'Concatenate with Join and separate each element with a 3-character string
concatenatedString = VBA.Strings.Join(widgetNames, " > ")
'concatenatedString = "foo > bar > fizz"
'Concatenate with Join and separate each element with a zero-width string
concatenatedString = VBA.Strings.Join(widgetNames, vbNullString)
'concatenatedString = "foobarfizz"
Section 7.2: Concatenate strings using the & operator
Const string1 As String = "foo"
Const string2 As String = "bar"
Const string3 As String = "fizz"
Dim concatenatedString As String
'Concatenate two strings
concatenatedString = string1 & string2
'concatenatedString = "foobar"
'Concatenate three strings
concatenatedString = string1 & string2 & string3
'concatenatedString = "foobarfizz"
GoalKicker.com – VBA Notes for Professionals 27
Chapter 8: Frequently used string
manipulation
Quick examples for MID LEFT and RIGHT string functions using INSTR FIND and LEN.
How do you find the text between two search terms (Say: after a colon and before a comma)? How do you get the
remainder of a word (using MID or using RIGHT)? Which of these functions use Zero-based params and return
codes vs One-based? What happens when things go wrong? How do they handle empty strings, unfound results
and negative numbers?
Section 8.1: String manipulation frequently used examples
Better MID() and other string extraction examples, currently lacking from the web. Please help me make a good
example, or complete this one here. Something like this:
DIM strEmpty as String, strNull as String, theText as String
DIM idx as Integer
DIM letterCount as Integer
DIM result as String
strNull = NOTHING
strEmpty = ""
theText = "1234, 78910"
' -----------------
' Extract the word after the comma ", " and before "910" result: "78" ***
' -----------------
' Get index (place) of comma using INSTR
idx = ... ' some explanation here
if idx < ... ' check if no comma found in text
' or get index of comma using FIND
idx = ... ' some explanation here... Note: The difference is...
if idx < ... ' check if no comma found in text
result = MID(theText, ..., LEN(...
' Retrieve remaining word after the comma
result = MID(theText, idx+1, LEN(theText) - idx+1)
' Get word until the comma using LEFT
result = LEFT(theText, idx - 1)
' Get remaining text after the comma-and-space using RIGHT
result = ...
' What happens when things go wrong
result = MID(strNothing, 1, 2) ' this causes ...
result = MID(strEmpty, 1, 2) ' which causes...
result = MID(theText, 30, 2) ' and now...
result = MID(theText, 2, 999) ' no worries...
result = MID(theText, 0, 2)
result = MID(theText, 2, 0)
result = MID(theText -1, 2)
result = MID(theText 2, -1)
idx = INSTR(strNothing, "123")
idx = INSTR(theText, strNothing)
GoalKicker.com – VBA Notes for Professionals 28
idx = INSTR(theText, strEmpty)
i = LEN(strEmpty)
i = LEN(strNothing) '...
Please feel free to edit this example and make it better. As long as it remains clear, and has in it common usage
practices.
GoalKicker.com – VBA Notes for Professionals 29
Chapter 9: Substrings
Section 9.1: Use Left or Left$ to get the 3 left-most characters
in a string
Const baseString As String = "Foo Bar"
Dim leftText As String
leftText = Left$(baseString, 3)
'leftText = "Foo"
Section 9.2: Use Right or Right$ to get the 3 right-most
characters in a string
Const baseString As String = "Foo Bar"
Dim rightText As String
rightText = Right$(baseString, 3)
'rightText = "Bar"
Section 9.3: Use Mid or Mid$ to get specific characters from
within a string
Const baseString As String = "Foo Bar"
'Get the string starting at character 2 and ending at character 6
Dim midText As String
midText = Mid$(baseString, 2, 5)
'midText = "oo Ba"
Section 9.4: Use Trim to get a copy of the string without any
leading or trailing spaces
'Trim the leading and trailing spaces in a string
Const paddedText As String = " Foo Bar "
Dim trimmedText As String
trimmedText = Trim$(paddedText)
'trimmedText = "Foo Bar"
GoalKicker.com – VBA Notes for Professionals 30
Chapter 10: Searching within strings for
the presence of substrings
Section 10.1: Use InStr to determine if a string contains a
substring
Const baseString As String = "Foo Bar"
Dim containsBar As Boolean
'Check if baseString contains "bar" (case insensitive)
containsBar = InStr(1, baseString, "bar", vbTextCompare) > 0
'containsBar = True
'Check if baseString contains bar (case insensitive)
containsBar = InStr(1, baseString, "bar", vbBinaryCompare) > 0
'containsBar = False
Section 10.2: Use InStrRev to find the position of the last
instance of a substring
Const baseString As String = "Foo Bar"
Dim containsBar As Boolean
'Find the position of the last "B"
Dim posX As Long
'Note the different number and order of the parameters for InStrRev
posX = InStrRev(baseString, "X", -1, vbBinaryCompare)
'posX = 0
Section 10.3: Use InStr to find the position of the first instance
of a substring
Const baseString As String = "Foo Bar"
Dim containsBar As Boolean
Dim posB As Long
posB = InStr(1, baseString, "B", vbBinaryCompare)
'posB = 5
GoalKicker.com – VBA Notes for Professionals 31
Chapter 11: Assigning strings with repeated
characters
Section 11.1: Use the String function to assign a string with n
repeated characters
Dim lineOfHyphens As String
'Assign a string with 80 repeated hyphens
lineOfHyphens = String$(80, "-")
Section 11.2: Use the String and Space functions to assign an
n-character string
Dim stringOfSpaces As String
'Assign a string with 255 repeated spaces using Space$
stringOfSpaces = Space$(255)
'Assign a string with 255 repeated spaces using String$
stringOfSpaces = String$(255, " ")
GoalKicker.com – VBA Notes for Professionals 32
Chapter 12: Measuring the length of strings
Section 12.1: Use the Len function to determine the number of
characters in a string
Const baseString As String = "Hello World"
Dim charLength As Long
charLength = Len(baseString)
'charlength = 11
Section 12.2: Use the LenB function to determine the number
of bytes in a string
Const baseString As String = "Hello World"
Dim byteLength As Long
byteLength = LenB(baseString)
'byteLength = 22
Section 12.3: Prefer `If Len(myString) = 0 Then` over `If
myString = "" Then`
When checking if a string is zero-length, it is better practice, and more efficient, to inspect the length of the string
rather than comparing the string to an empty string.
Const myString As String = vbNullString
'Prefer this method when checking if myString is a zero-length string
If Len(myString) = 0 Then
Debug.Print "myString is zero-length"
End If
'Avoid using this method when checking if myString is a zero-length string
If myString = vbNullString Then
Debug.Print "myString is zero-length"
End If
GoalKicker.com – VBA Notes for Professionals 33
Chapter 13: Converting other types to
strings
Section 13.1: Use CStr to convert a numeric type to a string
Const zipCode As Long = 10012
Dim zipCodeText As String
'Convert the zipCode number to a string of digit characters
zipCodeText = CStr(zipCode)
'zipCodeText = "10012"
Section 13.2: Use Format to convert and format a numeric
type as a string
Const zipCode As long = 10012
Dim zeroPaddedNumber As String
zeroPaddedZipCode = Format(zipCode, "00000000")
'zeroPaddedNumber = "00010012"
Section 13.3: Use StrConv to convert a byte-array of singlebyte
characters to a string
'Declare an array of bytes, assign single-byte character codes, and convert to a string
Dim singleByteChars(4) As Byte
singleByteChars(0) = 72
singleByteChars(1) = 101
singleByteChars(2) = 108
singleByteChars(3) = 108
singleByteChars(4) = 111
Dim stringFromSingleByteChars As String
stringFromSingleByteChars = StrConv(singleByteChars, vbUnicode)
'stringFromSingleByteChars = "Hello"
Section 13.4: Implicitly convert a byte array of multi-bytecharacters
to a string
'Declare an array of bytes, assign multi-byte character codes, and convert to a string
Dim multiByteChars(9) As Byte
multiByteChars(0) = 87
multiByteChars(1) = 0
multiByteChars(2) = 111
multiByteChars(3) = 0
multiByteChars(4) = 114
multiByteChars(5) = 0
multiByteChars(6) = 108
multiByteChars(7) = 0
multiByteChars(8) = 100
multiByteChars(9) = 0
Dim stringFromMultiByteChars As String
stringFromMultiByteChars = multiByteChars
'stringFromMultiByteChars = "World"
GoalKicker.com – VBA Notes for Professionals 34
Chapter 14: Date Time Manipulation
Section 14.1: Calendar
VBA supports 2 calendars : Gregorian and Hijri
The Calendar property is used to modify or display the current calendar.
The 2 values for the Calendar are:
Value Constant Description
0 vbCalGreg Gregorian calendar (default)
1 vbCalHijri Hijri calendar
Example
Sub CalendarExample()
'Cache the current setting.
Dim Cached As Integer
Cached = Calendar
' Dates in Gregorian Calendar
Calendar = vbCalGreg
Dim Sample As Date
'Create sample date of 2016-07-28
Sample = DateSerial(2016, 7, 28)
Debug.Print "Current Calendar : " & Calendar
Debug.Print "SampleDate = " & Format$(Sample, "yyyy-mm-dd")
' Date in Hijri Calendar
Calendar = vbCalHijri
Debug.Print "Current Calendar : " & Calendar
Debug.Print "SampleDate = " & Format$(Sample, "yyyy-mm-dd")
'Reset VBA to cached value.
Calendar = Cached
End Sub
This Sub prints the following ;
Current Calendar : 0
SampleDate = 2016-07-28
Current Calendar : 1
SampleDate = 1437-10-23
Section 14.2: Base functions
Retrieve System DateTime
VBA supports 3 built-in functions to retrieve the date and/or time from the system's clock.
Function Return Type Return Value
Now Date Returns the current date and time
Date Date Returns the date portion of the current date and time
Time Date Returns the time portion of the current date and time
GoalKicker.com – VBA Notes for Professionals 35
Sub DateTimeExample()
' Note : EU system with default date format DD/MM/YYYY
Debug.Print Now ' prints 28/07/2016 10:16:01 (output below assumes this date and time)
Debug.Print Date ' prints 28/07/2016
Debug.Print Time ' prints 10:16:01
' Apply a custom format to the current date or time
Debug.Print Format$(Now, "dd mmmm yyyy hh:nn") ' prints 28 July 2016 10:16
Debug.Print Format$(Date, "yyyy-mm-dd") ' prints 2016-07-28
Debug.Print Format$(Time, "hh") & " hour " & _
Format$(Time, "nn") & " min " & _
Format$(Time, "ss") & " sec " ' prints 10 hour 16 min 01 sec
End Sub
Timer Function
The Timer function returns a Single representing the number of seconds elapsed since midnight. The precision is
one hundredth of a second.
Sub TimerExample()
Debug.Print Time ' prints 10:36:31 (time at execution)
Debug.Print Timer ' prints 38191,13 (seconds since midnight)
End Sub
Because Now and Time functions are only precise to seconds, Timer offers a convenient way to increase accuracy of
time measurement:
Sub GetBenchmark()
Dim StartTime As Single
StartTime = Timer 'Store the current Time
Dim i As Long
Dim temp As String
For i = 1 To 1000000 'See how long it takes Left$ to execute 1,000,000 times
temp = Left$("Text", 2)
Next i
Dim Elapsed As Single
Elapsed = Timer - StartTime
Debug.Print "Code completed in " & CInt(Elapsed * 1000) & " ms"
End Sub
IsDate()
IsDate() tests whether an expression is a valid date or not. Returns a Boolean.
Sub IsDateExamples()
Dim anything As Variant
GoalKicker.com – VBA Notes for Professionals 36
anything = "September 11, 2001"
Debug.Print IsDate(anything) 'Prints True
anything = #9/11/2001#
Debug.Print IsDate(anything) 'Prints True
anything = "just a string"
Debug.Print IsDate(anything) 'Prints False
anything = vbNull
Debug.Print IsDate(anything) 'Prints False
End Sub
Section 14.3: Extraction functions
These functions take a Variant that can be cast to a Date as a parameter and return an Integer representing a
portion of a date or time. If the parameter can not be cast to a Date, it will result in a run-time error 13: Type
mismatch.
Function Description Returned value
Year() Returns the year portion of the date argument. Integer (100 to 9999)
Month() Returns the month portion of the date argument. Integer (1 to 12)
Day() Returns the day portion of the date argument. Integer (1 to 31)
WeekDay() Returns the day of the week of the date argument. Accepts an optional second
argument definining the first day of the week Integer (1 to 7)
Hour() Returns the hour portion of the date argument. Integer (0 to 23)
Minute() Returns the minute portion of the date argument. Integer (0 to 59)
Second() Returns the second portion of the date argument. Integer (0 to 59)
Examples:
Sub ExtractionExamples()
Dim MyDate As Date
MyDate = DateSerial(2016, 7, 28) + TimeSerial(12, 34, 56)
Debug.Print Format$(MyDate, "yyyy-mm-dd hh:nn:ss") ' prints 2016-07-28 12:34:56
Debug.Print Year(MyDate) ' prints 2016
Debug.Print Month(MyDate) ' prints 7
Debug.Print Day(MyDate) ' prints 28
Debug.Print Hour(MyDate) ' prints 12
Debug.Print Minute(MyDate) ' prints 34
Debug.Print Second(MyDate) ' prints 56
Debug.Print Weekday(MyDate) ' prints 5
'Varies by locale - i.e. will print 4 in the EU and 5 in the US
Debug.Print Weekday(MyDate, vbUseSystemDayOfWeek)
Debug.Print Weekday(MyDate, vbMonday) ' prints 4
Debug.Print Weekday(MyDate, vbSunday) ' prints 5
GoalKicker.com – VBA Notes for Professionals 37
End Sub
DatePart() Function
DatePart() is also a function returning a portion of a date, but works differently and allow more possibilities than
the functions above. It can for instance return the Quarter of the year or the Week of the year.
Syntax:
DatePart ( interval, date [, firstdayofweek] [, firstweekofyear] )
interval argument can be :
Interval Description
"yyyy" Year (100 to 9999)
"y" Day of the year (1 to 366)
"m" Month (1 to 12)
"q" Quarter (1 to 4)
"ww" Week (1 to 53)
"w" Day of the week (1 to 7)
"d" Day of the month (1 to 31)
"h" Hour (0 to 23)
"n" Minute (0 to 59)
"s" Second (0 to 59)
firstdayofweek is optional. it is a constant that specifies the first day of the week. If not specified, vbSunday is
assumed.
firstweekofyear is optional. it is a constant that specifies the first week of the year. If not specified, the first week is
assumed to be the week in which January 1 occurs.
Examples:
Sub DatePartExample()
Dim MyDate As Date
MyDate = DateSerial(2016, 7, 28) + TimeSerial(12, 34, 56)
Debug.Print Format$(MyDate, "yyyy-mm-dd hh:nn:ss") ' prints 2016-07-28 12:34:56
Debug.Print DatePart("yyyy", MyDate) ' prints 2016
Debug.Print DatePart("y", MyDate) ' prints 210
Debug.Print DatePart("h", MyDate) ' prints 12
Debug.Print DatePart("Q", MyDate) ' prints 3
Debug.Print DatePart("w", MyDate) ' prints 5
Debug.Print DatePart("ww", MyDate) ' prints 31
End Sub
Section 14.4: Calculation functions
DateDiff()
GoalKicker.com – VBA Notes for Professionals 38
DateDiff() returns a Long representing the number of time intervals between two specified dates.
Syntax
DateDiff ( interval, date1, date2 [, firstdayofweek] [, firstweekofyear] )
interval can be any of the intervals defined in the DatePart() function
date1 and date2 are the two dates you want to use in the calculation
firstdayofweek and firstweekofyear are optional. Refer to DatePart() function for explanations
Examples
Sub DateDiffExamples()
' Check to see if 2016 is a leap year.
Dim NumberOfDays As Long
NumberOfDays = DateDiff("d", #1/1/2016#, #1/1/2017#)
If NumberOfDays = 366 Then
Debug.Print "2016 is a leap year." 'This will output.
End If
' Number of seconds in a day
Dim StartTime As Date
Dim EndTime As Date
StartTime = TimeSerial(0, 0, 0)
EndTime = TimeSerial(24, 0, 0)
Debug.Print DateDiff("s", StartTime, EndTime) 'prints 86400
End Sub
DateAdd()
DateAdd() returns a Date to which a specified date or time interval has been added.
Syntax
DateAdd ( interval, number, date )
interval can be any of the intervals defined in the DatePart() function
number Numeric expression that is the number of intervals you want to add. It can be positive (to get dates in
the future) or negative (to get dates in the past).
date is a Date or literal representing date to which the interval is added
Examples :
Sub DateAddExamples()
Dim Sample As Date
'Create sample date and time of 2016-07-28 12:34:56
Sample = DateSerial(2016, 7, 28) + TimeSerial(12, 34, 56)
' Date 5 months previously (prints 2016-02-28):
Debug.Print Format$(DateAdd("m", -5, Sample), "yyyy-mm-dd")
' Date 10 months previously (prints 2015-09-28):
Debug.Print Format$(DateAdd("m", -10, Sample), "yyyy-mm-dd")
GoalKicker.com – VBA Notes for Professionals 39
' Date in 8 months (prints 2017-03-28):
Debug.Print Format$(DateAdd("m", 8, Sample), "yyyy-mm-dd")
' Date/Time 18 hours previously (prints 2016-07-27 18:34:56):
Debug.Print Format$(DateAdd("h", -18, Sample), "yyyy-mm-dd hh:nn:ss")
' Date/Time in 36 hours (prints 2016-07-30 00:34:56):
Debug.Print Format$(DateAdd("h", 36, Sample), "yyyy-mm-dd hh:nn:ss")
End Sub
Section 14.5: Conversion and Creation
CDate()
CDate() converts something from any datatype to a Date datatype
Sub CDateExamples()
Dim sample As Date
' Converts a String representing a date and time to a Date
sample = CDate("September 11, 2001 12:34")
Debug.Print Format$(sample, "yyyy-mm-dd hh:nn:ss") ' prints 2001-09-11 12:34:00
' Converts a String containing a date to a Date
sample = CDate("September 11, 2001")
Debug.Print Format$(sample, "yyyy-mm-dd hh:nn:ss") ' prints 2001-09-11 00:00:00
' Converts a String containing a time to a Date
sample = CDate("12:34:56")
Debug.Print Hour(sample) ' prints 12
Debug.Print Minute(sample) ' prints 34
Debug.Print Second(sample) ' prints 56
' Find the 10000th day from the epoch date of 1899-12-31
sample = CDate(10000)
Debug.Print Format$(sample, "yyyy-mm-dd") ' prints 1927-05-18
End Sub
Note that VBA also has a loosely typed CVDate() that functions in the same way as the CDate() function other than
returning a date typed Variant instead of a strongly typed Date. The CDate() version should be preferred when
passing to a Date parameter or assigning to a Date variable, and the CVDate() version should be preferred when
when passing to a Variant parameter or assigning to a Variant variable. This avoids implicit type casting.
DateSerial()
DateSerial() function is used to create a date. It returns a Date for a specified year, month, and day.
Syntax:
DateSerial ( year, month, day )
With year, month and day arguments being valid Integers (Year from 100 to 9999, Month from 1 to 12, Day from 1
to 31).
GoalKicker.com – VBA Notes for Professionals 40
Examples
Sub DateSerialExamples()
' Build a specific date
Dim sample As Date
sample = DateSerial(2001, 9, 11)
Debug.Print Format$(sample, "yyyy-mm-dd") ' prints 2001-09-11
' Find the first day of the month for a date.
sample = DateSerial(Year(sample), Month(sample), 1)
Debug.Print Format$(sample, "yyyy-mm-dd") ' prints 2001-09-11
' Find the last day of the previous month.
sample = DateSerial(Year(sample), Month(sample), 1) - 1
Debug.Print Format$(sample, "yyyy-mm-dd") ' prints 2001-09-11
End Sub
Note that DateSerial() will accept "invalid" dates and calculate a valid date from it. This can be used creatively for
good:
Positive Example
Sub GoodDateSerialExample()
'Calculate 45 days from today
Dim today As Date
today = DateSerial (2001, 9, 11)
Dim futureDate As Date
futureDate = DateSerial(Year(today), Month(today), Day(today) + 45)
Debug.Print Format$(futureDate, "yyyy-mm-dd") 'prints 2009-10-26
End Sub
However, it is more likely to cause grief when attempting to create a date from unvalidated user input:
Negative Example
Sub BadDateSerialExample()
'Allow user to enter unvalidate date information
Dim myYear As Long
myYear = InputBox("Enter Year")
'Assume user enters 2009
Dim myMonth As Long
myMonth = InputBox("Enter Month")
'Assume user enters 2
Dim myDay As Long
myDay = InputBox("Enter Day")
'Assume user enters 31
Debug.Print Format$(DateSerial(myYear, myMonth, myDay), "yyyy-mm-dd")
'prints 2009-03-03
End Sub
GoalKicker.com – VBA Notes for Professionals 41
Chapter 15: Data Types and Limits
Section 15.1: Variant
Dim Value As Variant 'Explicit
Dim Value 'Implicit
A Variant is a COM data type that is used for storing and exchanging values of arbitrary types, and any other type in
VBA can be assigned to a Variant. Variables declared without an explicit type specified by As [Type] default to
Variant.
Variants are stored in memory as a VARIANT structure that consists of a byte type descriptor (VARTYPE) followed by
6 reserved bytes then an 8 byte data area. For numeric types (including Date and Boolean), the underlying value is
stored in the Variant itself. For all other types, the data area contains a pointer to the underlying value.
The underlying type of a Variant can be determined with either the VarType() function which returns the numeric
value stored in the type descriptor, or the TypeName() function which returns the string representation:
Dim Example As Variant
Example = 42
Debug.Print VarType(Example) 'Prints 2 (VT_I2)
Debug.Print TypeName(Example) 'Prints "Integer"
Example = "Some text"
Debug.Print VarType(Example) 'Prints 8 (VT_BSTR)
Debug.Print TypeName(Example) 'Prints "String"
Because Variants can store values of any type, assignments from literals without type hints will be implicitly cast to
a Variant of the appropriate type according to the table below. Literals with type hints will be cast to a Variant of the
hinted type.
Value Resulting type
String values String
Non-floating point numbers in Integer range Integer
Non-floating point numbers in Long range Long
Non-floating point numbers outside of Long range Double
All floating point numbers Double
Note: Unless there is a specific reason to use a Variant (i.e. an iterator in a For Each loop or an API requirement),
the type should generally be avoided for routine tasks for the following reasons:
They are not type safe, increasing the possibility of runtime errors. For example, a Variant holding an Integer
value will silently change itself into a Long instead of overflowing.
They introduce processing overhead by requiring at least one additional pointer dereference.
The memory requirement for a Variant is always at least 8 bytes higher than needed to store the underlying
type.
The casting function to convert to a Variant is CVar().
GoalKicker.com – VBA Notes for Professionals 42
Section 15.2: Boolean
Dim Value As Boolean
A Boolean is used to store values that can be represented as either True or False. Internally, the data type is stored
as a 16 bit value with 0 representing False and any other value representing True.
It should be noted that when a Boolean is cast to a numeric type, all of the bits are set to 1. This results in an
internal representation of -1 for signed types and the maximum value for an unsigned type (Byte).
Dim Example As Boolean
Example = True
Debug.Print CInt(Example) 'Prints -1
Debug.Print CBool(42) 'Prints True
Debug.Print CByte(True) 'Prints 255
The casting function to convert to a Boolean is CBool(). Even though it is represented internally as a 16 bit number,
casting to a Boolean from values outside of that range is safe from overflow, although it sets all 16 bits to 1:
Dim Example As Boolean
Example = CBool(2 ^ 17)
Debug.Print CInt(Example) 'Prints -1
Debug.Print CByte(Example) 'Prints 255
Section 15.3: String
A String represents a sequence of characters, and comes in two flavors:
Variable length
Dim Value As String
A variable length String allows appending and truncation and is stored in memory as a COM BSTR. This consists of a
4 byte unsigned integer that stores the length of the String in bytes followed by the string data itself as wide
characters (2 bytes per character) and terminated with 2 null bytes. Thus, the maximum string length that can be
handled by VBA is 2,147,483,647 characters.
The internal pointer to the structure (retrievable by the StrPtr() function) points to the memory location of the
data, not the length prefix. This means that a VBA String can be passed directly API functions that require a pointer
to a character array.
Because the length can change, VBA reallocates memory for a String every time the variable is assigned to, which can
impose performance penalties for procedures that alter them repeatedly.
Fixed length
Dim Value As String * 1024 'Declares a fixed length string of 1024 characters.
Fixed length strings are allocated 2 bytes for each character and are stored in memory as a simple byte array. Once
allocated, the length of the String is immutable. They are not null terminated in memory, so a string that fills the
memory allocated with non-null characters is unsuitable for passing to API functions expecting a null terminated
string.
Fixed length strings carry over a legacy 16 bit index limitation, so can only be up to 65,535 characters in length.
Attempting to assign a value longer than the available memory space will not result in a runtime error - instead the
resulting value will simply be truncated:
GoalKicker.com – VBA Notes for Professionals 43
Dim Foobar As String * 5
Foobar = "Foo" & "bar"
Debug.Print Foobar 'Prints "Fooba"
The casting function to convert to a String of either type is CStr().
Section 15.4: Byte
Dim Value As Byte
A Byte is an unsigned 8 bit data type. It can represent integer numbers between 0 and 255 and attempting to store
a value outside of that range will result in runtime error 6: Overflow. Byte is the only intrinsic unsigned type
available in VBA.
The casting function to convert to a Byte is CByte(). For casts from floating point types, the result is rounded to the
nearest integer value with .5 rounding up.
Byte Arrays and Strings
Strings and byte arrays can be substituted for one another through simple assignment (no conversion functions
necessary).
For example:
Sub ByteToStringAndBack()
Dim str As String
str = "Hello, World!"
Dim byt() As Byte
byt = str
Debug.Print byt(0) ' 72
Dim str2 As String
str2 = byt
Debug.Print str2 ' Hello, World!
End Sub
In order to be able to encode Unicode characters, each character in the string takes up two bytes in the array, with
the least significant byte first. For example:
Sub UnicodeExample()
Dim str As String
str = ChrW(&H2123) & "." ' Versicle character and a dot
Dim byt() As Byte
byt = str
Debug.Print byt(0), byt(1), byt(2), byt(3) ' Prints: 35,33,46,0
End Sub
GoalKicker.com – VBA Notes for Professionals 44
Section 15.5: Currency
Dim Value As Currency
A Currency is a signed 64 bit floating point data type similar to a Double, but scaled by 10,000 to give greater
precision to the 4 digits to the right of the decimal point. A Currency variable can store values from
-922,337,203,685,477.5808 to 922,337,203,685,477.5807, giving it the largest capacity of any intrinsic type in a 32 bit
application. As the name of the data type implies, it is considered best practice to use this data type when
representing monetary calculations as the scaling helps to avoid rounding errors.
The casting function to convert to a Currency is CCur().
Section 15.6: Decimal
Dim Value As Variant
Value = CDec(1.234)
'Set Value to the smallest possible Decimal value
Value = CDec("0.0000000000000000000000000001")
The Decimal data-type is only available as a sub-type of Variant, so you must declare any variable that needs to
contain a Decimal as a Variant and then assign a Decimal value using the CDec function. The keyword Decimal is a
reserved word (which suggests that VBA was eventually going to add first-class support for the type), so Decimal
cannot be used as a variable or procedure name.
The Decimal type requires 14 bytes of memory (in addition to the bytes required by the parent Variant) and can
store numbers with up to 28 decimal places. For numbers without any decimal places, the range of allowed values
is -79,228,162,514,264,337,593,543,950,335 to +79,228,162,514,264,337,593,543,950,335 inclusive. For numbers
with the maximum 28 decimal places, the range of allowed values is -7.9228162514264337593543950335 to
+7.9228162514264337593543950335 inclusive.
Section 15.7: Integer
Dim Value As Integer
An Integer is a signed 16 bit data type. It can store integer numbers in the range of -32,768 to 32,767 and
attempting to store a value outside of that range will result in runtime error 6: Overflow.
Integers are stored in memory as little-endian values with negatives represented as a two's complement.
Note that in general, it is better practice to use a Long rather than an Integer unless the smaller type is a member of
a Type or is required (either by an API calling convention or some other reason) to be 2 bytes. In most cases VBA
treats Integers as 32 bit internally, so there is usually no advantage to using the smaller type. Additionally, there is a
performance penalty incurred every time an Integer type is used as it is silently cast as a Long.
The casting function to convert to an Integer is CInt(). For casts from floating point types, the result is rounded to
the nearest integer value with .5 rounding up.
Section 15.8: Long
Dim Value As Long
A Long is a signed 32 bit data type. It can store integer numbers in the range of -2,147,483,648 to 2,147,483,647 and
GoalKicker.com – VBA Notes for Professionals 45
attempting to store a value outside of that range will result in runtime error 6: Overflow.
Longs are stored in memory as little-endian values with negatives represented as a two's complement.
Note that since a Long matches the width of a pointer in a 32 bit operating system, Longs are commonly used for
storing and passing pointers to and from API functions.
The casting function to convert to a Long is CLng(). For casts from floating point types, the result is rounded to the
nearest integer value with .5 rounding up.
Section 15.9: Single
Dim Value As Single
A Single is a signed 32 bit floating point data type. It is stored internally using a little-endian IEEE 754 memory
layout. As such, there is not a fixed range of values that can be represented by the data type - what is limited is the
precision of value stored. A Single can store a value integer values in the range of -16,777,216 to 16,777,216 without
a loss of precision. The precision of floating point numbers depends on the exponent.
A Single will overflow if assigned a value greater than roughly 2128. It will not overflow with negative exponents,
although the usable precision will be questionable before the upper limit is reached.
As with all floating point numbers, care should be taken when making equality comparisons. Best practice is to
include a delta value appropriate to the required precision.
The casting function to convert to a Single is CSng().
Section 15.10: Double
Dim Value As Double
A Double is a signed 64 bit floating point data type. Like the Single, it is stored internally using a little-endian IEEE
754 memory layout and the same precautions regarding precision should be taken. A Double can store integer
values in the range of -9,007,199,254,740,992 to 9,007,199,254,740,992 without a loss of precision. The precision of
floating point numbers depends on the exponent.
A Double will overflow if assigned a value greater than roughly 21024. It will not overflow with negative exponents,
although the usable precision will be questionable before the upper limit is reached.
The casting function to convert to a Double is CDbl().
Section 15.11: Date
Dim Value As Date
A Date type is represented internally as a signed 64 bit floating point data type with the value to the left of the
decimal representing the number of days from the epoch date of December 30th, 1899 (although see the note
below). The value to the right of the decimal represents the time as a fractional day. Thus, an integer Date would
have a time component of 12:00:00AM and x.5 would have a time component of 12:00:00PM.
Valid values for Dates are between January 1st 100 and December 31st 9999. Since a Double has a larger range, it is
possible to overflow a Date by assigning values outside of that range.
GoalKicker.com – VBA Notes for Professionals 46
As such, it can be used interchangeably with a Double for Date calculations:
Dim MyDate As Double
MyDate = 0 'Epoch date.
Debug.Print Format$(MyDate, "yyyy-mm-dd") 'Prints 1899-12-30.
MyDate = MyDate + 365
Debug.Print Format$(MyDate, "yyyy-mm-dd") 'Prints 1900-12-30.
The casting function to convert to a Date is CDate(), which accepts any numeric type string date/time
representation. It is important to note that string representations of dates will be converted based on the current
locale setting in use, so direct casts should be avoided if the code is meant to be portable.
Section 15.12: LongLong
Dim Value As LongLong
A LongLong is a signed 64 bit data type and is only available in 64 bit applications. It is not available in 32 bit
applications running on 64 bit operating systems. It can store integer values in the range of
-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 and attempting to store a value outside of that range will
result in runtime error 6: Overflow.
LongLongs are stored in memory as little-endian values with negatives represented as a two's complement.
The LongLong data type was introduced as part of VBA's 64 bit operating system support. In 64 bit applications, this
value can be used to store and pass pointers to 64 bit APIs.
The casting function to convert to a LongLong is CLngLng(). For casts from floating point types, the result is
rounded to the nearest integer value with .5 rounding up.
Section 15.13: LongPtr
Dim Value As LongPtr
The LongPtr was introduced into VBA in order to support 64 bit platforms. On a 32 bit system, it is treated as a Long
and on 64 bit systems it is treated as a LongLong.
It's primary use is in providing a portable way to store and pass pointers on both architectures (See Changing code
behavior at compile time.
Although it is treated by the operating system as a memory address when used in API calls, it should be noted that
VBA treats it like signed type (and therefore subject to unsigned to signed overflow). For this reason, any pointer
arithmetic performed using LongPtrs should not use > or < comparisons. This "quirk" also makes it possible that
adding simple offsets pointing to valid addresses in memory can cause overflow errors, so caution should be taken
when working with pointers in VBA.
The casting function to convert to a LongPtr is CLngPtr(). For casts from floating point types, the result is rounded
to the nearest integer value with .5 rounding up (although since it is usually a memory address, using it as an
assignment target for a floating point calculation is dangerous at best).
GoalKicker.com – VBA Notes for Professionals 47
Chapter 16: Naming Conventions
Section 16.1: Variable Names
Variables hold data. Name them after what they're used for, not after their data type or scope, using a noun. If
you feel compelled to number your variables (e.g. thing1, thing2, thing3), then consider using an appropriate
data structure instead (e.g. an array, a Collection, or a Dictionary).
Names of variables that represent an iteratable set of values - e.g. an array, a Collection, a Dictionary, or a Range
of cells, should be plural.
Some common VBA naming conventions go thus:
For procedure-level Variables:
camelCase
Public Sub ExampleNaming(ByVal inputValue As Long, ByRef inputVariable As Long)
Dim procedureVariable As Long
Dim someOtherVariable As String
End Sub
For module-level Variables:
PascalCase
Public GlobalVariable As Long
Private ModuleVariable As String
For Constants:
SHOUTY_SNAKE_CASE is commonly used to differentiate constants from variables:
Public Const GLOBAL_CONSTANT As String = "Project Version #1.000.000.001"
Private Const MODULE_CONSTANT As String = "Something relevant to this Module"
Public Sub SomeProcedure()
Const PROCEDURE_CONSTANT As Long = 10
End Sub
However PascalCase names make cleaner-looking code and are just as good, given IntelliSense uses different icons
for variables and constants:
GoalKicker.com – VBA Notes for Professionals 48
Hungarian Notation
Name them after what they're used for, not after their data type or scope.
"Hungarian Notation makes it easier to see what the type of a variable is"
If you write your code such as procedures adhere to the Single Responsibility Principle (as it should), you should
never be looking at a screenful of variable declarations at the top of any procedure; declare variables as close as
possible to their first usage, and their data type will always be in plain sight if you declare them with an explicit type.
The VBE's Ctrl + i shortcut can be used to display a variable's type in a tooltip, too.
What a variable is used for is much more useful information than its data type, especially in a language such as VBA
which happily and implicitly converts a type into another as needed.
Consider iFile and strFile in this example:
Function bReadFile(ByVal strFile As String, ByRef strData As String) As Boolean
Dim bRetVal As Boolean
Dim iFile As Integer
On Error GoTo CleanFail
iFile = FreeFile
Open strFile For Input As #iFile
Input #iFile, strData
bRetVal = True
CleanExit:
Close #iFile
bReadFile = bRetVal
Exit Function
CleanFail:
bRetVal = False
Resume CleanExit
End Function
Compare to:
Function CanReadFile(ByVal path As String, ByRef outContent As String) As Boolean
On Error GoTo CleanFail
Dim handle As Integer
handle = FreeFile
GoalKicker.com – VBA Notes for Professionals 49
Open path For Input As #handle
Input #handle, outContent
Dim result As Boolean
result = True
CleanExit:
Close #handle
CanReadFile = result
Exit Function
CleanFail:
result = False
Resume CleanExit
End Function
strData is passed ByRef in the top example, but beside the fact that we're lucky enough to see that it's explicitly
passed as such, there's no indication that strData is actually returned by the function.
The bottom example names it outContent; this out prefix is what Hungarian Notation was invented for: to help
clarify what a variable is used for, in this case to clearly identify it as an "out" parameter.
This is useful, because IntelliSense by itself doesn't display ByRef, even when the parameter is explicitly passed by
reference:
Which leads to...
Hungarian Done Right
Hungarian Notation originally didn't have anything to do with variable types. In fact, Hungarian Notation done right
is actually useful. Consider this small example (ByVal and As Integer removed for brevety):
Public Sub Copy(iX1, iY1, iX2, iY2)
End Sub
Compare to:
Public Sub Copy(srcColumn, srcRow, dstColumn, dstRow)
End Sub
src and dst are Hungarian Notation prefixes here, and they convey useful information that cannot otherwise already
be inferred from the parameter names or IntelliSense showing us the declared type.
Of course there's a better way to convey it all, using proper abstraction and real words that can be pronounced out
loud and make sense - as a contrived example:
Type Coordinate
RowIndex As Long
ColumnIndex As Long
End Type
Sub Copy(source As Coordinate, destination As Coordinate)
End Sub
GoalKicker.com – VBA Notes for Professionals 50
Section 16.2: Procedure Names
Procedures do something. Name them after what they're doing, using a verb. If accurately naming a procedure is
not possible, likely the procedure is doing too many things and needs to be broken down into smaller, more
specialized procedures.
Some common VBA naming conventions go thus:
For all Procedures:
PascalCase
Public Sub DoThing()
End Sub
Private Function ReturnSomeValue() As [DataType]
End Function
For event handler procedures:
ObjectName_EventName
Public Sub Workbook_Open()
End Sub
Public Sub Button1_Click()
End Sub
Event handlers are usually automatically named by the VBE; renaming them without renaming the object and/or
the handled event will break the code - the code will run and compile, but the handler procedure will be orphaned
and will never be executed.
Boolean Members
Consider a Boolean-returning function:
Function bReadFile(ByVal strFile As String, ByRef strData As String) As Boolean
End Function
Compare to:
Function CanReadFile(ByVal path As String, ByRef outContent As String) As Boolean
End Function
The Can prefix does serve the same purpose as the b prefix: it identifies the function's return value as a Boolean. But
Can reads better than b:
If CanReadFile(path, content) Then
Compared to:
If bReadFile(strFile, strData) Then
GoalKicker.com – VBA Notes for Professionals 51
Consider using prefixes such as Can, Is or Has in front of Boolean-returning members (functions and properties),
but only when it adds value. This conforms with the current Microsoft naming guidelines.
GoalKicker.com – VBA Notes for Professionals 52
Chapter 17: Data Structures
[TODO: This topic should be an example of all the basic CS 101 data structures along with some explanation as an
overview of how data structures can be implemented in VBA. This would be a good opportunity to tie in and
reinforce concepts introduced in Class-related topics in VBA documentation.]
Section 17.1: Linked List
This linked list example implements Set abstract data type operations.
SinglyLinkedNode class
Option Explicit
Private Value As Variant
Private NextNode As SinglyLinkedNode '"Next" is a keyword in VBA and therefore is not a valid
variable name
LinkedList class
Option Explicit
Private head As SinglyLinkedNode
'Set type operations
Public Sub Add(value As Variant)
Dim node As SinglyLinkedNode
Set node = New SinglyLinkedNode
node.value = value
Set node.nextNode = head
Set head = node
End Sub
Public Sub Remove(value As Variant)
Dim node As SinglyLinkedNode
Dim prev As SinglyLinkedNode
Set node = head
While Not node Is Nothing
If node.value = value Then
'remove node
If node Is head Then
Set head = node.nextNode
Else
Set prev.nextNode = node.nextNode
End If
Exit Sub
End If
Set prev = node
Set node = node.nextNode
Wend
End Sub
GoalKicker.com – VBA Notes for Professionals 53
Public Function Exists(value As Variant) As Boolean
Dim node As SinglyLinkedNode
Set node = head
While Not node Is Nothing
If node.value = value Then
Exists = True
Exit Function
End If
Set node = node.nextNode
Wend
End Function
Public Function Count() As Long
Dim node As SinglyLinkedNode
Set node = head
While Not node Is Nothing
Count = Count + 1
Set node = node.nextNode
Wend
End Function
Section 17.2: Binary Tree
This is an example of an unbalanced binary search tree. A binary tree is structured conceptually as a hierarchy of
nodes descending downward from a common root, where each node has two children: left and right. For example,
suppose the numbers 7, 5, 9, 3, 11, 6, 12, 14 and 15 were inserted into a BinaryTree. The structure would be as
below. Note that this binary tree is not balanced, which can be a desirable characteristic for guaranteeing the
performance of lookups - see AVL trees for an example of a self-balancing binary search tree.
7
/ \
5 9
/ \ \
3 6 11
\
12
\
14
\
15
BinaryTreeNode class
Option Explicit
Public left As BinaryTreeNode
Public right As BinaryTreeNode
Public key As Variant
Public value As Variant
BinaryTree class
[TODO]
GoalKicker.com – VBA Notes for Professionals 54
Chapter 18: Arrays
Section 18.1: Multidimensional Arrays
Multidimensional Arrays
As the name indicates, multi dimensional arrays are arrays that contain more than one dimension, usually two or
three but it can have up to 32 dimensions.
A multi array works like a matrix with various levels, take in example a comparison between one, two, and three
Dimensions.
One Dimension is your typical array, it looks like a list of elements.
Dim 1D(3) as Variant
*1D - Visually*
(0)
(1)
(2)
Two Dimensions would look like a Sudoku Grid or an Excel sheet, when initializing the array you would define how
many rows and columns the array would have.
Dim 2D(3,3) as Variant
'this would result in a 3x3 grid
*2D - Visually*
(0,0) (0,1) (0,2)
(1,0) (1,1) (1,2)
(2,0) (2,1) (2,2)
Three Dimensions would start to look like Rubik's Cube, when initializing the array you would define rows and
columns and layers/depths the array would have.
Dim 3D(3,3,2) as Variant
'this would result in a 3x3x3 grid
*3D - Visually*
1st layer 2nd layer 3rd layer
front middle back
(0,0,0) (0,0,1) (0,0,2) ¦ (1,0,0) (1,0,1) (1,0,2) ¦ (2,0,0) (2,0,1) (2,0,2)
(0,1,0) (0,1,1) (0,1,2) ¦ (1,1,0) (1,1,1) (1,1,2) ¦ (2,1,0) (2,1,1) (2,1,2)
(0,2,0) (0,2,1) (0,2,2) ¦ (1,2,0) (1,2,1) (1,2,2) ¦ (2,2,0) (2,2,1) (2,2,2)
Further dimensions could be thought as the multiplication of the 3D, so a 4D(1,3,3,3) would be two side-by-side 3D
arrays.
Two-Dimension Array
Creating
The example below will be a compilation of a list of employees, each employee will have a set of information on the
list (First Name, Surname, Address, Email, Phone ...), the example will essentially be storing on the array
GoalKicker.com – VBA Notes for Professionals 55
(employee,information) being the (0,0) is the first employee's first name.
Dim Bosses As Variant
'set bosses as Variant, so we can input any data type we want
Bosses = [{"Jonh","Snow","President";"Ygritte","Wild","Vice-President"}]
'initialise a 2D array directly by filling it with information, the redult wil be a array(1,2) size
2x3 = 6 elements
Dim Employees As Variant
'initialize your Employees array as variant
'initialize and ReDim the Employee array so it is a dynamic array instead of a static one, hence
treated differently by the VBA Compiler
ReDim Employees(100, 5)
'declaring an 2D array that can store 100 employees with 6 elements of information each, but starts
empty
'the array size is 101 x 6 and contains 606 elements
For employee = 0 To UBound(Employees, 1)
'for each employee/row in the array, UBound for 2D arrays, which will get the last element on the
array
'needs two parameters 1st the array you which to check and 2nd the dimension, in this case 1 =
employee and 2 = information
For information_e = 0 To UBound(Employees, 2)
'for each information element/column in the array
Employees(employee, information_e) = InformationNeeded ' InformationNeeded would be the
data to fill the array
'iterating the full array will allow for direct attribution of information into the element
coordinates
Next
Next
Resizing
Resizing or ReDim Preserve a Multi-Array like the norm for a One-Dimension array would get an error, instead the
information needs to be transferred into a Temporary array with the same size as the original plus the number of
row/columns to add. In the example below we'll see how to initialize a Temp Array, transfer the information over
from the original array, fill the remaining empty elements, and replace the temp array by the original array.
Dim TempEmp As Variant
'initialise your temp array as variant
ReDim TempEmp(UBound(Employees, 1) + 1, UBound(Employees, 2))
'ReDim/Resize Temp array as a 2D array with size UBound(Employees)+1 = (last element in Employees 1st
dimension) + 1,
'the 2nd dimension remains the same as the original array. we effectively add 1 row in the Employee
array
'transfer
For emp = LBound(Employees, 1) To UBound(Employees, 1)
For info = LBound(Employees, 2) To UBound(Employees, 2)
'to transfer Employees into TempEmp we iterate both arrays and fill TempEmp with the
corresponding element value in Employees
TempEmp(emp, info) = Employees(emp, info)
Next
Next
'fill remaining
'after the transfers the Temp array still has unused elements at the end, being that it was increased
GoalKicker.com – VBA Notes for Professionals 56
'to fill the remaining elements iterate from the last "row" with values to the last row in the array
'in this case the last row in Temp will be the size of the Employees array rows + 1, as the last row
of Employees array is already filled in the TempArray
For emp = UBound(Employees, 1) + 1 To UBound(TempEmp, 1)
For info = LBound(TempEmp, 2) To UBound(TempEmp, 2)
TempEmp(emp, info) = InformationNeeded & "NewRow"
Next
Next
'erase Employees, attribute Temp array to Employees and erase Temp array
Erase Employees
Employees = TempEmp
Erase TempEmp
Changing Element Values
To change/alter the values in a certain element can be done by simply calling the coordinate to change and giving it
a new value: Employees(0, 0) = "NewValue"
Alternatively iterate through the coordinates use conditions to match values corresponding to the parameters
needed:
For emp = 0 To UBound(Employees)
If Employees(emp, 0) = "Gloria" And Employees(emp, 1) = "Stephan" Then
'if value found
Employees(emp, 1) = "Married, Last Name Change"
Exit For
'don't iterate through a full array unless necessary
End If
Next
Reading
Accessing the elements in the array can be done with a Nested Loop (iterating every element), Loop and Coordinate
(iterate Rows and accessing columns directly), or accessing directly with both coordinates.
'nested loop, will iterate through all elements
For emp = LBound(Employees, 1) To UBound(Employees, 1)
For info = LBound(Employees, 2) To UBound(Employees, 2)
Debug.Print Employees(emp, info)
Next
Next
'loop and coordinate, iteration through all rows and in each row accessing all columns directly
For emp = LBound(Employees, 1) To UBound(Employees, 1)
Debug.Print Employees(emp, 0)
Debug.Print Employees(emp, 1)
Debug.Print Employees(emp, 2)
Debug.Print Employees(emp, 3)
Debug.Print Employees(emp, 4)
Debug.Print Employees(emp, 5)
Next
'directly accessing element with coordinates
GoalKicker.com – VBA Notes for Professionals 57
Debug.Print Employees(5, 5)
Remember, it's always handy to keep an array map when using Multidimensional arrays, they can easily become
confusion.
Three-Dimension Array
For the 3D array, we'll use the same premise as the 2D array, with the addition of not only storing the Employee
and Information but as well Building they work in.
The 3D array will have the Employees (can be thought of as Rows), the Information (Columns), and Building that can
be thought of as different sheets on an excel document, they have the same size between them, but every sheets
has a different set of information in its cells/elements. The 3D array will contain n number of 2D arrays.
Creating
A 3D array needs 3 coordinates to be initialized Dim 3Darray(2,5,5) As Variant the first coordinate on the array
will be the number of Building/Sheets (different sets of rows and columns), second coordinate will define Rows and
third Columns. The Dim above will result in a 3D array with 108 elements (3*6*6), effectively having 3 different sets
of 2D arrays.
Dim ThreeDArray As Variant
'initialise your ThreeDArray array as variant
ReDim ThreeDArray(1, 50, 5)
'declaring an 3D array that can store two sets of 51 employees with 6 elements of information each,
but starts empty
'the array size is 2 x 51 x 6 and contains 612 elements
For building = 0 To UBound(ThreeDArray, 1)
'for each building/set in the array
For employee = 0 To UBound(ThreeDArray, 2)
'for each employee/row in the array
For information_e = 0 To UBound(ThreeDArray, 3)
'for each information element/column in the array
ThreeDArray(building, employee, information_e) = InformationNeeded ' InformationNeeded
would be the data to fill the array
'iterating the full array will allow for direct attribution of information into the element
coordinates
Next
Next
Next
Resizing
Resizing a 3D array is similar to resizing a 2D, first create a Temporary array with the same size of the original
adding one in the coordinate of the parameter to increase, the first coordinate will increase the number of sets in
the array, the second and third coordinates will increase the number of Rows or Columns in each set.
The example below increases the number of Rows in each set by one, and fills those recently added elements with
new information.
Dim TempEmp As Variant
'initialise your temp array as variant
ReDim TempEmp(UBound(ThreeDArray, 1), UBound(ThreeDArray, 2) + 1, UBound(ThreeDArray, 3))
GoalKicker.com – VBA Notes for Professionals 58
'ReDim/Resize Temp array as a 3D array with size UBound(ThreeDArray)+1 = (last element in Employees
2nd dimension) + 1,
'the other dimension remains the same as the original array. we effectively add 1 row in the for each
set of the 3D array
'transfer
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
For info = LBound(ThreeDArray, 3) To UBound(ThreeDArray, 3)
'to transfer ThreeDArray into TempEmp by iterating all sets in the 3D array and fill
TempEmp with the corresponding element value in each set of each row
TempEmp(building, emp, info) = ThreeDArray(building, emp, info)
Next
Next
Next
'fill remaining
'to fill the remaining elements we need to iterate from the last "row" with values to the last row in
the array in each set, remember that the first empty element is the original array Ubound() plus 1
For building = LBound(TempEmp, 1) To UBound(TempEmp, 1)
For emp = UBound(ThreeDArray, 2) + 1 To UBound(TempEmp, 2)
For info = LBound(TempEmp, 3) To UBound(TempEmp, 3)
TempEmp(building, emp, info) = InformationNeeded & "NewRow"
Next
Next
Next
'erase Employees, attribute Temp array to Employees and erase Temp array
Erase ThreeDArray
ThreeDArray = TempEmp
Erase TempEmp
Changing Element Values and Reading
Reading and changing the elements on the 3D array can be done similarly to the way we do the 2D array, just adjust
for the extra level in the loops and coordinates.
Do
' using Do ... While for early exit
For building = 0 To UBound(ThreeDArray, 1)
For emp = 0 To UBound(ThreeDArray, 2)
If ThreeDArray(building, emp, 0) = "Gloria" And ThreeDArray(building, emp, 1) =
"Stephan" Then
'if value found
ThreeDArray(building, emp, 1) = "Married, Last Name Change"
Exit Do
'don't iterate through all the array unless necessary
End If
Next
Next
Loop While False
'nested loop, will iterate through all elements
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
For info = LBound(ThreeDArray, 3) To UBound(ThreeDArray, 3)
Debug.Print ThreeDArray(building, emp, info)
Next
GoalKicker.com – VBA Notes for Professionals 59
Next
Next
'loop and coordinate, will iterate through all set of rows and ask for the row plus the value we
choose for the columns
For building = LBound(ThreeDArray, 1) To UBound(ThreeDArray, 1)
For emp = LBound(ThreeDArray, 2) To UBound(ThreeDArray, 2)
Debug.Print ThreeDArray(building, emp, 0)
Debug.Print ThreeDArray(building, emp, 1)
Debug.Print ThreeDArray(building, emp, 2)
Debug.Print ThreeDArray(building, emp, 3)
Debug.Print ThreeDArray(building, emp, 4)
Debug.Print ThreeDArray(building, emp, 5)
Next
Next
'directly accessing element with coordinates
Debug.Print Employees(0, 5, 5)
Section 18.2: Dynamic Arrays (Array Resizing and Dynamic
Handling)
Dynamic Arrays
Adding and reducing variables on an array dynamically is a huge advantage for when the information you are
treating does not have a set number of variables.
Adding Values Dynamically
You can simply resize the Array with the ReDim Statement, this will resize the array but to if you which to retain the
information already stored in the array you'll need the part Preserve.
In the example below we create an array and increase it by one more variable in each iteration while preserving the
values already in the array.
Dim Dynamic_array As Variant
' first we set Dynamic_array as variant
For n = 1 To 100
If IsEmpty(Dynamic_array) Then
'isempty() will check if we need to add the first value to the array or subsequent ones
ReDim Dynamic_array(0)
'ReDim Dynamic_array(0) will resize the array to one variable only
Dynamic_array(0) = n
Else
ReDim Preserve Dynamic_array(0 To UBound(Dynamic_array) + 1)
'in the line above we resize the array from variable 0 to the UBound() = last variable, plus
one effectivelly increeasing the size of the array by one
Dynamic_array(UBound(Dynamic_array)) = n
'attribute a value to the last variable of Dynamic_array
End If
Next
Removing Values Dynamically
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We can utilise the same logic to to decrease the the array. In the example the value "last" will be removed from the
array.
Dim Dynamic_array As Variant
Dynamic_array = Array("first", "middle", "last")
ReDim Preserve Dynamic_array(0 To UBound(Dynamic_array) - 1)
' Resize Preserve while dropping the last value
Resetting an Array and Reusing Dynamically
We can as well re-utilise the arrays we create as not to have many on memory, which would make the run time
slower. This is useful for arrays of various sizes. One snippet you could use to re-utilise the array is to ReDim the
array back to (0), attribute one variable to to the array and freely increase the array again.
In the snippet below I construct an array with the values 1 to 40, empty the array, and refill the array with values 40
to 100, all this done dynamically.
Dim Dynamic_array As Variant
For n = 1 To 100
If IsEmpty(Dynamic_array) Then
ReDim Dynamic_array(0)
Dynamic_array(0) = n
ElseIf Dynamic_array(0) = "" Then
'if first variant is empty ( = "") then give it the value of n
Dynamic_array(0) = n
Else
ReDim Preserve Dynamic_array(0 To UBound(Dynamic_array) + 1)
Dynamic_array(UBound(Dynamic_array)) = n
End If
If n = 40 Then
ReDim Dynamic_array(0)
'Resizing the array back to one variable without Preserving,
'leaving the first value of the array empty
End If
Next
Section 18.3: Jagged Arrays (Arrays of Arrays)
Jagged Arrays NOT Multidimensional Arrays
Arrays of Arrays(Jagged Arrays) are not the same as Multidimensional Arrays if you think about them visually
Multidimensional Arrays would look like Matrices (Rectangular) with defined number of elements on their
dimensions(inside arrays), while Jagged array would be like a yearly calendar with the inside arrays having different
number of elements, like days in on different months.
Although Jagged Arrays are quite messy and tricky to use due to their nested levels and don't have much type
safety, but they are very flexible, allow you to manipulate different types of data quite easily, and don't need to
contain unused or empty elements.
Creating a Jagged Array
In the below example we will initialise a jagged array containing two arrays one for Names and another for
GoalKicker.com – VBA Notes for Professionals 61
Numbers, and then accessing one element of each
Dim OuterArray() As Variant
Dim Names() As Variant
Dim Numbers() As Variant
'arrays are declared variant so we can access attribute any data type to its elements
Names = Array("Person1", "Person2", "Person3")
Numbers = Array("001", "002", "003")
OuterArray = Array(Names, Numbers)
'Directly giving OuterArray an array containing both Names and Numbers arrays inside
Debug.Print OuterArray(0)(1)
Debug.Print OuterArray(1)(1)
'accessing elements inside the jagged by giving the coordenades of the element
Dynamically Creating and Reading Jagged Arrays
We can as well be more dynamic in our approx to construct the arrays, imagine that we have a customer data sheet
in excel and we want to construct an array to output the customer details.
Name - Phone - Email - Customer Number
Person1 - 153486231 - 1@STACK - 001
Person2 - 153486242 - 2@STACK - 002
Person3 - 153486253 - 3@STACK - 003
Person4 - 153486264 - 4@STACK - 004
Person5 - 153486275 - 5@STACK - 005
We will Dynamically construct an Header array and a Customers array, the Header will contain the column titles and
the Customers array will contain the information of each customer/row as arrays.
Dim Headers As Variant
' headers array with the top section of the customer data sheet
For c = 1 To 4
If IsEmpty(Headers) Then
ReDim Headers(0)
Headers(0) = Cells(1, c).Value
Else
ReDim Preserve Headers(0 To UBound(Headers) + 1)
Headers(UBound(Headers)) = Cells(1, c).Value
End If
Next
Dim Customers As Variant
'Customers array will contain arrays of customer values
Dim Customer_Values As Variant
'Customer_Values will be an array of the customer in its elements (Name-Phone-Email-CustNum)
For r = 2 To 6
'iterate through the customers/rows
For c = 1 To 4
'iterate through the values/columns
'build array containing customer values
If IsEmpty(Customer_Values) Then
ReDim Customer_Values(0)
Customer_Values(0) = Cells(r, c).Value
ElseIf Customer_Values(0) = "" Then
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Customer_Values(0) = Cells(r, c).Value
Else
ReDim Preserve Customer_Values(0 To UBound(Customer_Values) + 1)
Customer_Values(UBound(Customer_Values)) = Cells(r, c).Value
End If
Next
'add customer_values array to Customers Array
If IsEmpty(Customers) Then
ReDim Customers(0)
Customers(0) = Customer_Values
Else
ReDim Preserve Customers(0 To UBound(Customers) + 1)
Customers(UBound(Customers)) = Customer_Values
End If
'reset Custumer_Values to rebuild a new array if needed
ReDim Customer_Values(0)
Next
Dim Main_Array(0 To 1) As Variant
'main array will contain both the Headers and Customers
Main_Array(0) = Headers
Main_Array(1) = Customers
To better understand the way to Dynamically construct a one dimensional array please check Dynamic
Arrays (Array Resizing and Dynamic Handling) on the Arrays documentation.
The Result of the above snippet is an Jagged Array with two arrays one of those arrays with 4 elements, 2 indention
levels, and the other being itself another Jagged Array containing 5 arrays of 4 elements each and 3 indention
levels, see below the structure:
Main_Array(0) - Headers - Array("Name","Phone","Email","Customer Number")
(1) - Customers(0) - Array("Person1",153486231,"1@STACK",001)
Customers(1) - Array("Person2",153486242,"2@STACK",002)
...
Customers(4) - Array("Person5",153486275,"5@STACK",005)
To access the information you'll have to bear in mind the structure of the Jagged Array you create, in the above
example you can see that the Main Array contains an Array of Headers and an Array of Arrays (Customers) hence
with different ways of accessing the elements.
Now we'll read the information of the Main Array and print out each of the Customers information as Info Type:
Info.
For n = 0 To UBound(Main_Array(1))
'n to iterate from first to last array in Main_Array(1)
For j = 0 To UBound(Main_Array(1)(n))
'j will iterate from first to last element in each array of Main_Array(1)
Debug.Print Main_Array(0)(j) & ": " & Main_Array(1)(n)(j)
'print Main_Array(0)(j) which is the header and Main_Array(0)(n)(j) which is the element in
the customer array
'we can call the header with j as the header array has the same structure as the customer
array
Next
Next
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REMEMBER to keep track of the structure of your Jagged Array, in the example above to access the Name of a
customer is by accessing Main_Array -> Customers -> CustomerNumber -> Name which is three levels, to return
"Person4" you'll need the location of Customers in the Main_Array, then the Location of customer four on the
Customers Jagged array and lastly the location of the element you need, in this case Main_Array(1)(3)(0) which is
Main_Array(Customers)(CustomerNumber)(Name).
Section 18.4: Declaring an Array in VBA
Declaring an array is very similar to declaring a variable, except you need to declare the dimension of the Array
right after its name:
Dim myArray(9) As String 'Declaring an array that will contain up to 10 strings
By default, Arrays in VBA are indexed from ZERO, thus, the number inside the parenthesis doesn't refer to the size
of the array, but rather to the index of the last element
Accessing Elements
Accessing an element of the Array is done by using the name of the Array, followed by the index of the element,
inside parenthesis:
myArray(0) = "first element"
myArray(5) = "sixth element"
myArray(9) = "last element"
Array Indexing
You can change Arrays indexing by placing this line at the top of a module:
Option Base 1
With this line, all Arrays declared in the module will be indexed from ONE.
Specific Index
You can also declare each Array with its own index by using the To keyword, and the lower and upper bound (=
index):
Dim mySecondArray(1 To 12) As String 'Array of 12 strings indexed from 1 to 12
Dim myThirdArray(13 To 24) As String 'Array of 12 strings indexed from 13 to 24
Dynamic Declaration
When you do not know the size of your Array prior to its declaration, you can use the dynamic declaration, and the
ReDim keyword:
Dim myDynamicArray() As Strings 'Creates an Array of an unknown number of strings
ReDim myDynamicArray(5) 'This resets the array to 6 elements
Note that using the ReDim keyword will wipe out any previous content of your Array. To prevent this, you can use
the Preserve keyword after ReDim:
Dim myDynamicArray(5) As String
myDynamicArray(0) = "Something I want to keep"
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ReDim Preserve myDynamicArray(8) 'Expand the size to up to 9 strings
Debug.Print myDynamicArray(0) ' still prints the element
Section 18.5: Use of Split to create an array from a string
Split Function
returns a zero-based, one dimensional array containing a specified number of substrings.
Syntax
Split(expression [, delimiter [, limit [, compare]]])
Part Description
expression
Required. String expression containing substrings and delimiters. If expression is a zero-length string(""
or vbNullString), Split returns an empty array containing no elements and no data. In this case, the
returned array will have a LBound of 0 and a UBound of -1.
delimiter
Optional. String character used to identify substring limits. If omitted, the space character (" ") is
assumed to be the delimiter. If delimiter is a zero-length string, a single-element array containing the
entire expression string is returned.
limit Optional. Number of substrings to be returned; -1 indicates that all substrings are returned.
compare Optional. Numeric value indicating the kind of comparison to use when evaluating substrings. See
Settings section for values.
Settings
The compare argument can have the following values:
Constant Value Description
Description -1 Performs a comparison using the setting of the Option Compare statement.
vbBinaryCompare 0 Performs a binary comparison.
vbTextCompare 1 Performs a textual comparison.
vbDatabaseCompare 2 Microsoft Access only. Performs a comparison based on information in your database.
Example
In this example it is demonstrated how Split works by showing several styles. The comments will show the result set
for each of the different performed Split options. Finally it is demonstrated how to loop over the returned string
array.
Sub Test
Dim textArray() as String
textArray = Split("Tech on the Net")
'Result: {"Tech", "on", "the", "Net"}
textArray = Split("172.23.56.4", ".")
'Result: {"172", "23", "56", "4"}
textArray = Split("A;B;C;D", ";")
'Result: {"A", "B", "C", "D"}
textArray = Split("A;B;C;D", ";", 1)
'Result: {"A;B;C;D"}
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textArray = Split("A;B;C;D", ";", 2)
'Result: {"A", "B;C;D"}
textArray = Split("A;B;C;D", ";", 3)
'Result: {"A", "B", "C;D"}
textArray = Split("A;B;C;D", ";", 4)
'Result: {"A", "B", "C", "D"}
'You can iterate over the created array
Dim counter As Long
For counter = LBound(textArray) To UBound(textArray)
Debug.Print textArray(counter)
Next
End Sub
Section 18.6: Iterating elements of an array
For...Next
Using the iterator variable as the index number is the fastest way to iterate the elements of an array:
Dim items As Variant
items = Array(0, 1, 2, 3)
Dim index As Integer
For index = LBound(items) To UBound(items)
'assumes value can be implicitly converted to a String:
Debug.Print items(index)
Next
Nested loops can be used to iterate multi-dimensional arrays:
Dim items(0 To 1, 0 To 1) As Integer
items(0, 0) = 0
items(0, 1) = 1
items(1, 0) = 2
items(1, 1) = 3
Dim outer As Integer
Dim inner As Integer
For outer = LBound(items, 1) To UBound(items, 1)
For inner = LBound(items, 2) To UBound(items, 2)
'assumes value can be implicitly converted to a String:
Debug.Print items(outer, inner)
Next
Next
For Each...Next
A For Each...Next loop can also be used to iterate arrays, if performance doesn't matter:
Dim items As Variant
items = Array(0, 1, 2, 3)
Dim item As Variant 'must be variant
For Each item In items
'assumes value can be implicitly converted to a String:
GoalKicker.com – VBA Notes for Professionals 66
Debug.Print item
Next
A For Each loop will iterate all dimensions from outer to inner (the same order as the elements are laid out in
memory), so there is no need for nested loops:
Dim items(0 To 1, 0 To 1) As Integer
items(0, 0) = 0
items(1, 0) = 1
items(0, 1) = 2
items(1, 1) = 3
Dim item As Variant 'must be Variant
For Each item In items
'assumes value can be implicitly converted to a String:
Debug.Print item
Next
Note that For Each loops are best used to iterate Collection objects, if performance matters.
All 4 snippets above produce the same output:
0
1
2
3
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Chapter 19: Copying, returning and passing
arrays
Section 19.1: Passing Arrays to Proceedures
Arrays can be passed to proceedures by putting () after the name of the array variable.
Function countElements(ByRef arr() As Double) As Long
countElements = UBound(arr) - LBound(arr) + 1
End Function
Arrays must be passed by reference. If no passing mechanism is specified, e.g. myFunction(arr()), then VBA will
assume ByRef by default, however it is good coding practice to make it explicit. Trying to pass an array by value, e.g.
myFunction(ByVal arr()) will result in an "Array argument must be ByRef" compilation error (or a "Syntax error"
compilation error if Auto Syntax Check is not checked in the VBE options).
Passing by reference means that any changes to the array will be preserved in the calling proceedure.
Sub testArrayPassing()
Dim source(0 To 1) As Long
source(0) = 3
source(1) = 1
Debug.Print doubleAndSum(source) ' outputs 8
Debug.Print source(0); source(1) ' outputs 6 2
End Sub
Function doubleAndSum(ByRef arr() As Long)
arr(0) = arr(0) * 2
arr(1) = arr(1) * 2
doubleAndSum = arr(0) + arr(1)
End Function
If you want to avoid changing the original array then be careful to write the function so that it doesn't change any
elements.
Function doubleAndSum(ByRef arr() As Long)
doubleAndSum = arr(0) * 2 + arr(1) * 2
End Function
Alternatively create a working copy of the array and work with the copy.
Function doubleAndSum(ByRef arr() As Long)
Dim copyOfArr() As Long
copyOfArr = arr
copyOfArr(0) = copyOfArr(0) * 2
copyOfArr(1) = copyOfArr(1) * 2
doubleAndSum = copyOfArr(0) + copyOfArr(1)
End Function
Section 19.2: Copying Arrays
You can copy a VBA array into an array of the same type using the = operator. The arrays must be of the same type
GoalKicker.com – VBA Notes for Professionals 68
otherwise the code will throw a "Can't assign to array" compilation error.
Dim source(0 to 2) As Long
Dim destinationLong() As Long
Dim destinationDouble() As Double
destinationLong = source ' copies contents of source into destinationLong
destinationDouble = source ' does not compile
The source array can be fixed or dynamic, but the destination array must be dynamic. Trying to copy to a fixed
array will throw a "Can't assign to array" compilation error. Any preexisting data in the receiving array is lost and its
bounds and dimenions are changed to the same as the source array.
Dim source() As Long
ReDim source(0 To 2)
Dim fixed(0 To 2) As Long
Dim dynamic() As Long
fixed = source ' does not compile
dynamic = source ' does compile
Dim dynamic2() As Long
ReDim dynamic2(0 to 6, 3 to 99)
dynamic2 = source ' dynamic2 now has dimension (0 to 2)
Once the copy is made the two arrays are separate in memory, i.e. the two variables are not references to same
underlying data, so changes made to one array do not appear in the other.
Dim source(0 To 2) As Long
Dim destination() As Long
source(0) = 3
source(1) = 1
source(2) = 4
destination = source
destination(0) = 2
Debug.Print source(0); source(1); source(2) ' outputs: 3 1 4
Debug.Print destination(0); destination(1); destination(2) ' outputs: 2 1 4
Copying Arrays of Objects
With arrays of objects the references to those objects are copied, not the objects themselves. If a change is made to
an object in one array it will also appear to be changed in the other array - they are both referencing the same
object. However, setting an element to a different object in one array won't set it to that object the other array.
Dim source(0 To 2) As Range
Dim destination() As Range
Set source(0) = Range("A1"): source(0).Value = 3
Set source(1) = Range("A2"): source(1).Value = 1
Set source(2) = Range("A3"): source(2).Value = 4
destination = source
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Set destination(0) = Range("A4") 'reference changed in destination but not source
destination(0).Value = 2 'affects an object only in destination
destination(1).Value = 5 'affects an object in both source and destination
Debug.Print source(0); source(1); source(2) ' outputs 3 5 4
Debug.Print destination(0); destination(1); destination(2) ' outputs 2 5 4
Variants Containing an Array
You can also copy an array into and from a variant variable. When copying from a variant, it must contain an array
of the same type as the receiving array otherwise it will throw a "Type mismatch" runtime error.
Dim var As Variant
Dim source(0 To 2) As Range
Dim destination() As Range
var = source
destination = var
var = 5
destination = var ' throws runtime error
Section 19.3: Returning Arrays from Functions
A function in a normal module (but not a Class module) can return an array by putting () after the data type.
Function arrayOfPiDigits() As Long()
Dim outputArray(0 To 2) As Long
outputArray(0) = 3
outputArray(1) = 1
outputArray(2) = 4
arrayOfPiDigits = outputArray
End Function
The result of the function can then be put into a dynamic array of the same type or a variant. The elements can also
be accessed directly by using a second set of brackets, however this will call the function each time, so its best to
store the results in a new array if you plan to use them more than once
Sub arrayExample()
Dim destination() As Long
Dim var As Variant
destination = arrayOfPiDigits()
var = arrayOfPiDigits
Debug.Print destination(0) ' outputs 3
Debug.Print var(1) ' outputs 1
Debug.Print arrayOfPiDigits()(2) ' outputs 4
End Sub
Note that what is returned is actually a copy of the array inside the function, not a reference. So if the function
returns the contents of a Static array its data can't be changed by the calling procedure.
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Outputting an Array via an output argument
It is normally good coding practice for a procedure's arguments to be inputs and to output via the return value.
However, the limitations of VBA sometimes make it necessary for a procedure to output data via a ByRef argument.
Outputting to a fixed array
Sub threePiDigits(ByRef destination() As Long)
destination(0) = 3
destination(1) = 1
destination(2) = 4
End Sub
Sub printPiDigits()
Dim digits(0 To 2) As Long
threePiDigits digits
Debug.Print digits(0); digits(1); digits(2) ' outputs 3 1 4
End Sub
Outputting an Array from a Class method
An output argument can also be used to output an array from a method/proceedure in a Class module
' Class Module 'MathConstants'
Sub threePiDigits(ByRef destination() As Long)
ReDim destination(0 To 2)
destination(0) = 3
destination(1) = 1
destination(2) = 4
End Sub
' Standard Code Module
Sub printPiDigits()
Dim digits() As Long
Dim mathConsts As New MathConstants
mathConsts.threePiDigits digits
Debug.Print digits(0); digits(1); digits(2) ' outputs 3 1 4
End Sub
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Chapter 20: Collections
Section 20.1: Getting the Item Count of a Collection
The number of items in a Collection can be obtained by calling its .Count function:
Syntax:
.Count()
Sample Usage:
Public Sub Example()
Dim foo As New Collection
With foo
.Add "One"
.Add "Two"
.Add "Three"
.Add "Four"
End With
Debug.Print foo.Count 'Prints 4
End Sub
Section 20.2: Determining if a Key or Item Exists in a
Collection
Keys
Unlike a Scripting.Dictionary, a Collection does not have a method for determining if a given key exists or a way to
retrieve keys that are present in the Collection. The only method to determine if a key is present is to use the
error handler:
Public Function KeyExistsInCollection(ByVal key As String, _
ByRef container As Collection) As Boolean
With Err
If container Is Nothing Then .Raise 91
On Error Resume Next
Dim temp As Variant
temp = container.Item(key)
On Error GoTo 0
If .Number = 0 Then
KeyExistsInCollection = True
ElseIf .Number <> 5 Then
.Raise .Number
End If
End With
End Function
Items
The only way to determine if an item is contained in a Collection is to iterate over the Collection until the item is
located. Note that because a Collection can contain either primitives or objects, some extra handling is needed to
avoid run-time errors during the comparisons:
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Public Function ItemExistsInCollection(ByRef target As Variant, _
ByRef container As Collection) As Boolean
Dim candidate As Variant
Dim found As Boolean
For Each candidate In container
Select Case True
Case IsObject(candidate) And IsObject(target)
found = candidate Is target
Case IsObject(candidate), IsObject(target)
found = False
Case Else
found = (candidate = target)
End Select
If found Then
ItemExistsInCollection = True
Exit Function
End If
Next
End Function
Section 20.3: Adding Items to a Collection
Items are added to a Collection by calling its .Add method:
Syntax:
.Add(item, [key], [before, after])
Parameter Description
item The item to store in the Collection. This can be essentially any value that a variable can be assigned
to, including primitive types, arrays, objects, and Nothing.
key
Optional. A String that serves as a unique identifier for retrieving items from the Collection. If the
specified key already exists in the Collection, it will result in a Run-time error 457: "This key is already
associated with an element of this collection".
before
Optional. An existing key (String value) or index (numeric value) to insert the item before in the
Collection. If a value is given, the after parameter must be empty or a Run-time error 5: "Invalid
procedure call or argument" will result. If a String key is passed that does not exist in the Collection,
a Run-time error 5: "Invalid procedure call or argument" will result. If a numeric index is passed that is
does not exist in the Collection, a Run-time error 9: "Subscript out of range" will result.
after
Optional. An existing key (String value) or index (numeric value) to insert the item after in the
Collection. If a value is given, the before parameter must be empty. Errors raised are identical to the
before parameter.
Notes:
Keys are not case-sensitive. .Add "Bar", "Foo" and .Add "Baz", "foo" will result in a key collision.
If neither of the optional before or after parameters are given, the item will be added after the last item in the
Collection.
Insertions made by specifying a before or after parameter will alter the numeric indexes of existing members
to match thier new position. This means that care should be taken when making insertions in loops using
numeric indexes.
Sample Usage:
Public Sub Example()
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Dim foo As New Collection
With foo
.Add "One" 'No key. This item can only be retrieved by index.
.Add "Two", "Second" 'Key given. Can be retrieved by key or index.
.Add "Three", , 1 'Inserted at the start of the collection.
.Add "Four", , , 1 'Inserted at index 2.
End With
Dim member As Variant
For Each member In foo
Debug.Print member 'Prints "Three, Four, One, Two"
Next
End Sub
Section 20.4: Removing Items From a Collection
Items are removed from a Collection by calling its .Remove method:
Syntax:
.Remove(index)
Parameter Description
index
The item to remove from the Collection. If the value passed is a numeric type or Variant with a
numeric sub-type, it will be interpreted as a numeric index. If the value passed is a String or Variant
containing a string, it will be interpreted as the a key. If a String key is passed that does not exist in the
Collection, a Run-time error 5: "Invalid procedure call or argument" will result. If a numeric index is
passed that is does not exist in the Collection, a Run-time error 9: "Subscript out of range" will result.
Notes:
Removing an item from a Collection will change the numeric indexes of all the items after it in the
Collection. For loops that use numeric indexes and remove items should run backwards (Step -1) to
prevent subscript exceptions and skipped items.
Items should generally not be removed from a Collection from inside of a For Each loop as it can give
unpredictable results.
Sample Usage:
Public Sub Example()
Dim foo As New Collection
With foo
.Add "One"
.Add "Two", "Second"
.Add "Three"
.Add "Four"
End With
foo.Remove 1 'Removes the first item.
foo.Remove "Second" 'Removes the item with key "Second".
foo.Remove foo.Count 'Removes the last item.
Dim member As Variant
For Each member In foo
Debug.Print member 'Prints "Three"
Next
End Sub
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Section 20.5: Retrieving Items From a Collection
Items can be retrieved from a Collection by calling the .Item function.
Syntax:
.Item(index)
Parameter Description
index
The item to retrieve from the Collection. If the value passed is a numeric type or Variant with a
numeric sub-type, it will be interpreted as a numeric index. If the value passed is a String or Variant
containing a string, it will be interpreted as the a key. If a String key is passed that does not exist in the
Collection, a Run-time error 5: "Invalid procedure call or argument" will result. If a numeric index is
passed that is does not exist in the Collection, a Run-time error 9: "Subscript out of range" will result.
Notes:
.Item is the default member of Collection. This allows flexibility in syntax as demonstrated in the sample
usage below.
Numeric indexes are 1-based.
Keys are not case-sensitive. .Item("Foo") and .Item("foo") refer to the same key.
The index parameter is not implicitly cast to a number from a String or visa-versa. It is entirely possible that
.Item(1) and .Item("1") refer to different items of the Collection.
Sample Usage (Indexes):
Public Sub Example()
Dim foo As New Collection
With foo
.Add "One"
.Add "Two"
.Add "Three"
.Add "Four"
End With
Dim index As Long
For index = 1 To foo.Count
Debug.Print foo.Item(index) 'Prints One, Two, Three, Four
Next
End Sub
Sample Usage (Keys):
Public Sub Example()
Dim keys() As String
keys = Split("Foo,Bar,Baz", ",")
Dim values() As String
values = Split("One,Two,Three", ",")
Dim foo As New Collection
Dim index As Long
For index = LBound(values) To UBound(values)
foo.Add values(index), keys(index)
Next
Debug.Print foo.Item("Bar") 'Prints "Two"
End Sub
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Sample Usage (Alternate Syntax):
Public Sub Example()
Dim foo As New Collection
With foo
.Add "One", "Foo"
.Add "Two", "Bar"
.Add "Three", "Baz"
End With
'All lines below print "Two"
Debug.Print foo.Item("Bar") 'Explicit call syntax.
Debug.Print foo("Bar") 'Default member call syntax.
Debug.Print foo!Bar 'Bang syntax.
End Sub
Note that bang (!) syntax is allowed because .Item is the default member and can take a single String argument.
The utility of this syntax is questionable.
Section 20.6: Clearing All Items From a Collection
The easiest way to clear all of the items from a Collection is to simply replace it with a new Collection and let the
old one go out of scope:
Public Sub Example()
Dim foo As New Collection
With foo
.Add "One"
.Add "Two"
.Add "Three"
End With
Debug.Print foo.Count 'Prints 3
Set foo = New Collection
Debug.Print foo.Count 'Prints 0
End Sub
However, if there are multiple references to the Collection held, this method will only give you an empty
Collection for the variable that is assigned.
Public Sub Example()
Dim foo As New Collection
Dim bar As Collection
With foo
.Add "One"
.Add "Two"
.Add "Three"
End With
Set bar = foo
Set foo = New Collection
Debug.Print foo.Count 'Prints 0
Debug.Print bar.Count 'Prints 3
End Sub
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In this case, the easiest way to clear the contents is by looping through the number of items in the Collection and
repeatedly remove the lowest item:
Public Sub ClearCollection(ByRef container As Collection)
Dim index As Long
For index = 1 To container.Count
container.Remove 1
Next
End Sub
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Chapter 21: Operators
Section 21.1: Concatenation Operators
VBA supports 2 different concatenation operators, + and & and both perform the exact same function when used
with String types - the right-hand String is appended to the end of the left-hand String.
If the & operator is used with a variable type other than a String, it is implicitly cast to a String before being
concatenated.
Note that the + concatenation operator is an overload of the + addition operator. The behavior of + is determined
by the variable types of the operands and precedence of operator types. If both operands are typed as a String or
Variant with a sub-type of String, they are concatenated:
Public Sub Example()
Dim left As String
Dim right As String
left = "5"
right = "5"
Debug.Print left + right 'Prints "55"
End Sub
If either side is a numeric type and the other side is a String that can be coerced into a number, the type
precedence of mathematical operators causes the operator to be treated as the addition operator and the numeric
values are added:
Public Sub Example()
Dim left As Variant
Dim right As String
left = 5
right = "5"
Debug.Print left + right 'Prints 10
End Sub
This behavior can lead to subtle, hard to debug errors - especially if Variant types are being used, so only the &
operator should typically be used for concatenation.
Section 21.2: Comparison Operators
Token Name Description
= Equal to Returns True if the left-hand and right-hand operands are equal. Note that this is an
overload of the assignment operator.
<> Not equal to Returns True if the left-hand and right-hand operands are not equal.
> Greater than Returns True if the left-hand operand is greater than the right-hand operand.
< Less than Returns True if the left-hand operand is less than the right-hand operand.
>= Greater than or equal Returns True if the if the left-hand operand is greater than or equal to the right-hand
operand.
<= Less than or equal Returns True if the if the left-hand operand is less than or equal to the right-hand
operand.
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Is Reference equity
Returns True if the left-hand object reference is the same instance as the right-hand
object reference. It can also be used with Nothing (the null object reference) on
either side. Note: The Is operator will attempt to coerce both operands into an
Object before performing the comparison. If either side is a primitive type or a
Variant that does not contain an object (either a non-object subtype or vtEmpty),
the comparison will result in a Run-time error 424 - "Object required". If either
operand belongs to a different interface of the same object, the comparison will
return True. If you need to test for equity of both the instance and the interface, use
ObjPtr(left) = ObjPtr(right) instead.
Notes
The VBA syntax allows for "chains" of comparison operators, but these constructs should generally be avoided.
Comparisons are always performed from left to right on only 2 operands at a time, and each comparison results in
a Boolean. For example, the expression...
a = 2: b = 1: c = 0
expr = a > b > c
...may be read in some contexts as a test of whether b is between a and c. In VBA, this evaluates as follows:
a = 2: b = 1: c = 0
expr = a > b > c
expr = (2 > 1) > 0
expr = True > 0
expr = -1 > 0 'CInt(True) = -1
expr = False
Any comparison operator other than Is used with an Object as an operand will be performed on the return value
of the Object's default member. If the object does not have a default member, the comparison will result in a Runtime
error 438 - "Object doesn't support his property or method".
If the Object is unintitialized, the comparison will result in a Run-time error 91 - "Object variable or With block
variable not set".
If the literal Nothing is used with any comparison operator other than Is, it will result in a Compile error - "Invalid
use of object".
If the default member of the Object is another Object, VBA will continually call the default member of each
successive return value until a primitive type is returned or an error is raised. For example, assume SomeClass has a
default member of Value, which is an instance of ChildClass with a default member of ChildValue. The
comparison...
Set x = New SomeClass
Debug.Print x > 42
...will be evaluated as:
Set x = New SomeClass
Debug.Print x.Value.ChildValue > 42
If either operand is a numeric type and the other operand is a String or Variant of subtype String, a numeric
comparison will be performed. In this case, if the String cannot be cast to a number, a Run-time error 13 - "Type
mismatch" will result from the comparison.
If both operands are a String or a Variant of subtype String, a string comparison will be performed based on the
GoalKicker.com – VBA Notes for Professionals 79
Option Compare setting of the code module. These comparisons are performed on a character by character basis.
Note that the character representation of a String containing a number is not the same as a comparison of the
numeric values:
Public Sub Example()
Dim left As Variant
Dim right As Variant
left = "42"
right = "5"
Debug.Print left > right 'Prints False
Debug.Print Val(left) > Val(right) 'Prints True
End Sub
For this reason, make sure that String or Variant variables are cast to numbers before performing numeric
inequity comparisons on them.
If one operand is a Date, a numeric comparison on the underlying Double value will be performed if the other
operand is numeric or can be cast to a numeric type.
If the other operand is a String or a Variant of subtype String that can be cast to a Date using the current locale,
the String will be cast to a Date. If it cannot be cast to a Date in the current locale, a Run-time error 13 - "Type
mismatch" will result from the comparison.
Care should be taken when making comparisons between Double or Single values and Booleans. Unlike other
numeric types, non-zero values cannot be assumed to be True due to VBA's behavior of promoting the data type of
a comparison involving a floating point number to Double:
Public Sub Example()
Dim Test As Double
Test = 42 Debug.Print CBool(Test) 'Prints True.
'True is promoted to Double - Test is not cast to Boolean
Debug.Print Test = True 'Prints False
'With explicit casts:
Debug.Print CBool(Test) = True 'Prints True
Debug.Print CDbl(-1) = CDbl(True) 'Prints True
End Sub
Section 21.3: Bitwise \ Logical Operators
All of the logical operators in VBA can be thought of as "overrides" of the bitwise operators of the same name.
Technically, they are always treated as bitwise operators. All of the comparison operators in VBA return a Boolean,
which will always have none of its bits set (False) or all of its bits set (True). But it will treat a value with any bit set
as True. This means that the result of the casting the bitwise result of an expression to a Boolean (see Comparison
Operators) will always be the same as treating it as a logical expression.
Assigning the result of an expression using one of these operators will give the bitwise result. Note that in the truth
tables below, 0 is equivalent to False and 1 is equivalent to True.
And
Returns True if the expressions on both sides evaluate to True.
Left-hand Operand Right-hand Operand Result
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0 0 0
0 1 0
1 0 0
1 1 1
Or
Returns True if either side of the expression evaluates to True.
Left-hand Operand Right-hand Operand Result
0 0 0
0 1 1
1 0 1
1 1 1
Not
Returns True if the expression evaluates to False and False if the expression evaluations to True.
Right-hand Operand Result
0 1
1 0
Not is the only operand without a Left-hand operand. The Visual Basic Editor will automatically simplify expressions
with a left hand argument. If you type...
Debug.Print x Not y
...the VBE will change the line to:
Debug.Print Not x
Similar simplifications will be made to any expression that contains a left-hand operand (including expressions) for
Not.
Xor
Also known as "exclusive or". Returns True if both expressions evaluate to different results.
Left-hand Operand Right-hand Operand Result
0 0 0
0 1 1
1 0 1
1 1 0
Note that although the Xor operator can be used like a logical operator, there is absolutely no reason to do so as it
gives the same result as the comparison operator <>.
Eqv
Also known as "equivalence". Returns True when both expressions evaluate to the same result.
Left-hand Operand Right-hand Operand Result
0 0 1
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0 1 0
1 0 0
1 1 1
Note that the Eqv function is very rarely used as x Eqv y is equivalent to the much more readable Not (x Xor y).
Imp
Also known as "implication". Returns True if both operands are the same or the second operand is True.
Left-hand Operand Right-hand Operand Result
0 0 1
0 1 1
1 0 0
1 1 1
Note that the Imp function is very rarely used. A good rule of thumb is that if you can't explain what it means, you
should use another construct.
Section 21.4: Mathematical Operators
Listed in order of precedence:
Token Name Description
^ Exponentiation
Return the result of raising the left-hand operand to the power of the right-hand operand.
Note that the value returned by exponentiation is always a Double, regardless of the value
types being divided. Any coercion of the result into a variable type takes place after the
calculation is performed.
/ Division1
Returns the result of dividing the left-hand operand by the right-hand operand. Note that
the value returned by division is always a Double, regardless of the value types being
divided. Any coercion of the result into a variable type takes place after the calculation is
performed.
* Multiplication1 Returns the product of 2 operands.
\ Integer Division
Returns the integer result of dividing the left-hand operand by the right-hand operand
after rounding both sides with .5 rounding down. Any remainder of the division is ignored.
If the right-hand operand (the divisor) is 0, a Run-time error 11: Division by zero will result.
Note that this is after all rounding is performed - expressions such as 3 \ 0.4 will also
result in a division by zero error.
Mod Modulo
Returns the integer remainder of dividing the left-hand operand by the right-hand operand.
The operand on each side is rounded to an integer before the division, with .5 rounding
down. For example, both 8.6 Mod 3 and 12 Mod 2.6 result in 0. If the right-hand operand
(the divisor) is 0, a Run-time error 11: Division by zero will result. Note that this is after all
rounding is performed - expressions such as 3 Mod 0.4 will also result in a division by zero
error.
- Subtraction2 Returns the result of subtracting the right-hand operand from the left-hand operand.
+ Addition2 Returns the sum of 2 operands. Note that this token also treated as a concatenation
operator when it is applied to a String. See Concatenation Operators.
1 Multiplication and division are treated as having the same precedence.
2 Addition and subtraction are treated as having the same precedence.
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Chapter 22: Sorting
Unlike the .NET framework, the Visual Basic for Applications library does not include routines to sort arrays.
There are two types of workarounds: 1) implementing a sorting algorithm from scratch, or 2) using sorting routines
in other commonly-available libraries.
Section 22.1: Algorithm Implementation - Quick Sort on a One-
Dimensional Array
From VBA array sort function?
Public Sub QuickSort(vArray As Variant, inLow As Long, inHi As Long)
Dim pivot As Variant
Dim tmpSwap As Variant
Dim tmpLow As Long
Dim tmpHi As Long
tmpLow = inLow
tmpHi = inHi
pivot = vArray((inLow + inHi) \ 2)
While (tmpLow <= tmpHi)
While (vArray(tmpLow) < pivot And tmpLow < inHi)
tmpLow = tmpLow + 1
Wend
While (pivot < vArray(tmpHi) And tmpHi > inLow)
tmpHi = tmpHi - 1
Wend
If (tmpLow <= tmpHi) Then
tmpSwap = vArray(tmpLow)
vArray(tmpLow) = vArray(tmpHi)
vArray(tmpHi) = tmpSwap
tmpLow = tmpLow + 1
tmpHi = tmpHi - 1
End If
Wend
If (inLow < tmpHi) Then QuickSort vArray, inLow, tmpHi
If (tmpLow < inHi) Then QuickSort vArray, tmpLow, inHi
End Sub
Section 22.2: Using the Excel Library to Sort a One-
Dimensional Array
This code takes advantage of the Sort class in the Microsoft Excel Object Library.
For further reading, see:
Copy a range to a virtual range
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How to copy selected range into given array?
Sub testExcelSort()
Dim arr As Variant
InitArray arr
ExcelSort arr
End Sub
Private Sub InitArray(arr As Variant)
Const size = 10
ReDim arr(size)
Dim i As Integer
' Add descending numbers to the array to start
For i = 0 To size
arr(i) = size - i
Next i
End Sub
Private Sub ExcelSort(arr As Variant)
' Ininitialize the Excel objects (required)
Dim xl As New Excel.Application
Dim wbk As Workbook
Set wbk = xl.Workbooks.Add
Dim sht As Worksheet
Set sht = wbk.ActiveSheet
' Copy the array to the Range object
Dim rng As Range
Set rng = sht.Range("A1")
Set rng = rng.Resize(UBound(arr, 1), 1)
rng.Value = xl.WorksheetFunction.Transpose(arr)
' Run the worksheet's sort routine on the Range
Dim MySort As Sort
Set MySort = sht.Sort
With MySort
.SortFields.Clear
.SortFields.Add rng, xlSortOnValues, xlAscending, xlSortNormal
.SetRange rng
.Header = xlNo
.Apply
End With
' Copy the results back to the array
CopyRangeToArray rng, arr
' Clear the objects
Set rng = Nothing
wbk.Close False
xl.Quit
End Sub
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Private Sub CopyRangeToArray(rng As Range, arr)
Dim i As Long
Dim c As Range
' Can't just set the array to Range.value (adds a dimension)
For Each c In rng.Cells
arr(i) = c.Value
i = i + 1
Next c
End Sub
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Chapter 23: Flow control structures
Section 23.1: For loop
The For loop is used to repeat the enclosed section of code a given number of times. The following simple example
illustrates the basic syntax:
Dim i as Integer 'Declaration of i
For i = 1 to 10 'Declare how many times the loop shall be executed
Debug.Print i 'The piece of code which is repeated
Next i 'The end of the loop
The code above declares an Integer i. The For loop assigns every value between 1 and 10 to i and then executes
Debug.Print i - i.e. the code prints the numbers 1 through 10 to the immediate window. Note that the loop
variable is incremented by the Next statement, that is after the enclosed code executes as opposed to before it
executes.
By default, the counter will be incremented by 1 each time the loop executes. However, a Step can be specified to
change the amount of the increment as either a literal or the return value of a function. If the starting value, ending
value, or Step value is a floating point number, it will be rounded to the nearest integer value. Step can be either a
positive or negative value.
Dim i As Integer
For i = 1 To 10 Step 2
Debug.Print i 'Prints 1, 3, 5, 7, and 9
Next
In general a For loop would be used in situations where it is known before the loop starts how many times to
execute the enclosed code (otherwise a Do or While loop may be more appropriate). This is because the exit
condition is fixed after the first entry into loop, as this code demonstrates:
Private Iterations As Long 'Module scope
Public Sub Example()
Dim i As Long
Iterations = 10
For i = 1 To Iterations
Debug.Print Iterations 'Prints 10 through 1, descending.
Iterations = Iterations - 1
Next
End Sub
A For loop can be exited early with the Exit For statement:
Dim i As Integer
For i = 1 To 10
If i > 5 Then
Exit For
End If
Debug.Print i 'Prints 1, 2, 3, 4, 5 before loop exits early.
Next
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Section 23.2: Select Case
SELECT CASE can be used when many different conditions are possible. The conditions are checked from top to
bottom and only the first case that match will be executed.
Sub TestCase()
Dim MyVar As String
Select Case MyVar 'We Select the Variable MyVar to Work with
Case "Hello" 'Now we simply check the cases we want to check
MsgBox "This Case"
Case "World"
MsgBox "Important"
Case "How"
MsgBox "Stuff"
Case "Are"
MsgBox "I'm running out of ideas"
Case "You?", "Today" 'You can separate several conditions with a comma
MsgBox "Uuuhm..." 'if any is matched it will go into the case
Case Else 'If none of the other cases is hit
MsgBox "All of the other cases failed"
End Select
Dim i As Integer
Select Case i
Case Is > 2 '"Is" can be used instead of the variable in conditions.
MsgBox "i is greater than 2"
'Case 2 < Is '"Is" can only be used at the beginning of the condition.
'Case Else is optional
End Select
End Sub
The logic of the SELECT CASE block can be inverted to support testing of different variables too, in this kind of
scenario we can also use logical operators:
Dim x As Integer
Dim y As Integer
x = 2
y = 5
Select Case True
Case x > 3
MsgBox "x is greater than 3"
Case y < 2
MsgBox "y is less than 2"
Case x = 1
MsgBox "x is equal to 1"
Case x = 2 Xor y = 3
MsgBox "Go read about ""Xor"""
Case Not y = 5
MsgBox "y is not 5"
Case x = 3 Or x = 10
MsgBox "x = 3 or 10"
Case y < 10 And x < 10
MsgBox "x and y are less than 10"
Case Else
MsgBox "No match found"
End Select
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Case statements can also use arithmetic operators. Where an arithmetic operator is being used against the SELECT
CASE value it should be preceded with the Is keyword:
Dim x As Integer
x = 5
Select Case x
Case 1
MsgBox "x equals 1"
Case 2, 3, 4
MsgBox "x is 2, 3 or 4"
Case 7 To 10
MsgBox "x is between 7 and 10 (inclusive)"
Case Is < 2
MsgBox "x is less than one"
Case Is >= 7
MsgBox "x is greater than or equal to 7"
Case Else
MsgBox "no match found"
End Select
Section 23.3: For Each loop
The For Each loop construct is ideal for iterating all elements of a collection.
Public Sub IterateCollection(ByVal items As Collection)
'For Each iterator must always be variant
Dim element As Variant
For Each element In items
'assumes element can be converted to a string
Debug.Print element
Next
End Sub
Use For Each when iterating object collections:
Dim sheet As Worksheet
For Each sheet In ActiveWorkbook.Worksheets
Debug.Print sheet.Name
Next
Avoid For Each when iterating arrays; a For loop will offer significantly better performance with arrays. Conversely,
a For Each loop will offer better performance when iterating a Collection.
Syntax
For Each [item] In [collection]
[statements]
Next [item]
The Next keyword may optionally be followed by the iterator variable; this can help clarify nested loops, although
there are better ways to clarify nested code, such as extracting the inner loop into its own procedure.
Dim book As Workbook
For Each book In Application.Workbooks
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Debug.Print book.FullName
Dim sheet As Worksheet
For Each sheet In ActiveWorkbook.Worksheets
Debug.Print sheet.Name
Next sheet
Next book
Section 23.4: Do loop
Public Sub DoLoop()
Dim entry As String
entry = ""
'Equivalent to a While loop will ask for strings until "Stop" in given
'Prefer using a While loop instead of this form of Do loop
Do While entry <> "Stop"
entry = InputBox("Enter a string, Stop to end")
Debug.Print entry
Loop
'Equivalent to the above loop, but the condition is only checked AFTER the
'first iteration of the loop, so it will execute even at least once even
'if entry is equal to "Stop" before entering the loop (like in this case)
Do
entry = InputBox("Enter a string, Stop to end")
Debug.Print entry
Loop While entry <> "Stop"
'Equivalent to writing Do While Not entry="Stop"
'
'Because the Until is at the top of the loop, it will
'not execute because entry is still equal to "Stop"
'when evaluating the condition
Do Until entry = "Stop"
entry = InputBox("Enter a string, Stop to end")
Debug.Print entry
Loop
'Equivalent to writing Do ... Loop While Not i >= 100
Do
entry = InputBox("Enter a string, Stop to end")
Debug.Print entry
Loop Until entry = "Stop"
End Sub
Section 23.5: While loop
'Will return whether an element is present in the array
Public Function IsInArray(values() As String, ByVal whatToFind As String) As Boolean
Dim i As Integer
i = 0
While i < UBound(values) And values(i) <> whatToFind
i = i + 1
Wend
IsInArray = values(i) = whatToFind
End Function
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Chapter 24: Passing Arguments ByRef or
ByVal
The ByRef and ByVal modifiers are part of a procedure's signature and indicate how an argument is passed to a
procedure. In VBA a parameter is passed ByRef unless specified otherwise (i.e. ByRef is implicit if absent).
Note In many other programming languages (including VB.NET), parameters are implicitly passed by value if no
modifier is specified: consider specifying ByRef modifiers explicitly to avoid possible confusion.
Section 24.1: Passing Simple Variables ByRef And ByVal
Passing ByRef or ByVal indicates whether the actual value of an argument is passed to the CalledProcedure by the
CallingProcedure, or whether a reference (called a pointer in some other languages) is passed to the
CalledProcedure.
If an argument is passed ByRef, the memory address of the argument is passed to the CalledProcedure and any
modification to that parameter by the CalledProcedure is made to the value in the CallingProcedure.
If an argument is passed ByVal, the actual value, not a reference to the variable, is passed to the CalledProcedure.
A simple example will illustrate this clearly:
Sub CalledProcedure(ByRef X As Long, ByVal Y As Long)
X = 321
Y = 654
End Sub
Sub CallingProcedure()
Dim A As Long
Dim B As Long
A = 123
B = 456
Debug.Print "BEFORE CALL => A: " & CStr(A), "B: " & CStr(B)
''Result : BEFORE CALL => A: 123 B: 456
CalledProcedure X:=A, Y:=B
Debug.Print "AFTER CALL = A: " & CStr(A), "B: " & CStr(B)
''Result : AFTER CALL => A: 321 B: 456
End Sub
Another example:
Sub Main()
Dim IntVarByVal As Integer
Dim IntVarByRef As Integer
IntVarByVal = 5
IntVarByRef = 10
SubChangeArguments IntVarByVal, IntVarByRef '5 goes in as a "copy". 10 goes in as a reference
Debug.Print "IntVarByVal: " & IntVarByVal 'prints 5 (no change made by SubChangeArguments)
Debug.Print "IntVarByRef: " & IntVarByRef 'prints 99 (the variable was changed in
SubChangeArguments)
End Sub
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Sub SubChangeArguments(ByVal ParameterByVal As Integer, ByRef ParameterByRef As Integer)
ParameterByVal = ParameterByVal + 2 ' 5 + 2 = 7 (changed only inside this Sub)
ParameterByRef = ParameterByRef + 89 ' 10 + 89 = 99 (changes the IntVarByRef itself - in the
Main Sub)
End Sub
Section 24.2: ByRef
Default modifier
If no modifier is specified for a parameter, that parameter is implicitly passed by reference.
Public Sub DoSomething1(foo As Long)
End Sub
Public Sub DoSomething2(ByRef foo As Long)
End Sub
The foo parameter is passed ByRef in both DoSomething1 and DoSomething2.
Watch out! If you're coming to VBA with experience from other languages, this is very likely the exact
opposite behavior to the one you're used to. In many other programming languages (including VB.NET),
the implicit/default modifier passes parameters by value.
Passing by reference
When a value is passed ByRef, the procedure receives a reference to the value.
Public Sub Test()
Dim foo As Long
foo = 42
DoSomething foo
Debug.Print foo
End Sub
Private Sub DoSomething(ByRef foo As Long)
foo = foo * 2
End Sub
Calling the above Test procedure outputs 84. DoSomething is given foo and receives a reference to the value,
and therefore works with the same memory address as the caller.
When a reference is passed ByRef, the procedure receives a reference to the pointer.
Public Sub Test()
Dim foo As Collection
Set foo = New Collection
DoSomething foo
Debug.Print foo.Count
End Sub
Private Sub DoSomething(ByRef foo As Collection)
foo.Add 42
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Set foo = Nothing
End Sub
The above code raises run-time error 91, because the caller is calling the Count member of an object that no
longer exists, because DoSomething was given a reference to the object pointer and assigned it to Nothing
before returning.
Forcing ByVal at call site
Using parentheses at the call site, you can override ByRef and force an argument to be passed ByVal:
Public Sub Test()
Dim foo As Long
foo = 42
DoSomething (foo)
Debug.Print foo
End Sub
Private Sub DoSomething(ByRef foo As Long)
foo = foo * 2
End Sub
The above code outputs 42, regardless of whether ByRef is specified implicitly or explicitly.
Watch out! Because of this, using extraneous parentheses in procedure calls can easily introduce bugs.
Pay attention to the whitespace between the procedure name and the argument list:
bar = DoSomething(foo) 'function call, no whitespace; parens are part of args list
DoSomething (foo) 'procedure call, notice whitespace; parens are NOT part of args list
DoSomething foo 'procedure call does not force the foo parameter to be ByVal
Section 24.3: ByVal
Passing by value
When a value is passed ByVal, the procedure receives a copy of the value.
Public Sub Test()
Dim foo As Long
foo = 42
DoSomething foo
Debug.Print foo
End Sub
Private Sub DoSomething(ByVal foo As Long)
foo = foo * 2
End Sub
Calling the above Test procedure outputs 42. DoSomething is given foo and receives a copy of the value. The
copy is multiplied by 2, and then discarded when the procedure exits; the caller's copy was never altered.
When a reference is passed ByVal, the procedure receives a copy of the pointer.
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Public Sub Test()
Dim foo As Collection
Set foo = New Collection
DoSomething foo
Debug.Print foo.Count
End Sub
Private Sub DoSomething(ByVal foo As Collection)
foo.Add 42
Set foo = Nothing
End Sub
Calling the above Test procedure outputs 1. DoSomething is given foo and receives a copy of the pointer to
the Collection object. Because the foo object variable in the Test scope points to the same object, adding
an item in DoSomething adds the item to the same object. Because it's a copy of the pointer, setting its
reference to Nothing does not affect the caller's own copy.
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Chapter 25: Scripting.FileSystemObject
Section 25.1: Retrieve only the path from a file path
The GetParentFolderName method returns the parent folder for any path. While this can also be used with folders,
it is arguably more useful for extracting the path from an absolute file path:
Dim fso As New Scripting.FileSystemObject
Debug.Print fso.GetParentFolderName("C:\Users\Me\My Documents\SomeFile.txt")
Prints
C:\Users\Me\My Documents
Note that the trailing path separator is not included in the returned string.
Section 25.2: Retrieve just the extension from a file name
Dim fso As New Scripting.FileSystemObject
Debug.Print fso.GetExtensionName("MyFile.something.txt")
Prints txt Note that the GetExtensionName() method already handles multiple periods in a file name.
Section 25.3: Recursively enumerate folders and files
Early Bound (with a reference to Microsoft Scripting Runtime)
Sub EnumerateFilesAndFolders( _
FolderPath As String, _
Optional MaxDepth As Long = -1, _
Optional CurrentDepth As Long = 0, _
Optional Indentation As Long = 2)
Dim FSO As Scripting.FileSystemObject
Set FSO = New Scripting.FileSystemObject
'Check the folder exists
If FSO.FolderExists(FolderPath) Then
Dim fldr As Scripting.Folder
Set fldr = FSO.GetFolder(FolderPath)
'Output the starting directory path
If CurrentDepth = 0 Then
Debug.Print fldr.Path
End If
'Enumerate the subfolders
Dim subFldr As Scripting.Folder
For Each subFldr In fldr.SubFolders
Debug.Print Space$((CurrentDepth + 1) * Indentation) & subFldr.Name
If CurrentDepth < MaxDepth Or MaxDepth = -1 Then
'Recursively call EnumerateFilesAndFolders
EnumerateFilesAndFolders subFldr.Path, MaxDepth, CurrentDepth + 1, Indentation
End If
Next subFldr
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'Enumerate the files
Dim fil As Scripting.File
For Each fil In fldr.Files
Debug.Print Space$((CurrentDepth + 1) * Indentation) & fil.Name
Next fil
End If
End Sub
Output when called with arguments like: EnumerateFilesAndFolders "C:\Test"
C:\Test
Documents
Personal
Budget.xls
Recipes.doc
Work
Planning.doc
Downloads
FooBar.exe
ReadMe.txt
Output when called with arguments like: EnumerateFilesAndFolders "C:\Test", 0
C:\Test
Documents
Downloads
ReadMe.txt
Output when called with arguments like: EnumerateFilesAndFolders "C:\Test", 1, 4
C:\Test
Documents
Personal
Work
Downloads
FooBar.exe
ReadMe.txt
Section 25.4: Strip file extension from a file name
Dim fso As New Scripting.FileSystemObject
Debug.Print fso.GetBaseName("MyFile.something.txt")
Prints MyFile.something
Note that the GetBaseName() method already handles multiple periods in a file name.
Section 25.5: Enumerate files in a directory using
FileSystemObject
Early bound (requires a reference to Microsoft Scripting Runtime):
Public Sub EnumerateDirectory()
Dim fso As Scripting.FileSystemObject
Set fso = New Scripting.FileSystemObject
Dim targetFolder As Folder
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Set targetFolder = fso.GetFolder("C:\")
Dim foundFile As Variant
For Each foundFile In targetFolder.Files
Debug.Print foundFile.Name
Next
End Sub
Late bound:
Public Sub EnumerateDirectory()
Dim fso As Object
Set fso = CreateObject("Scripting.FileSystemObject")
Dim targetFolder As Object
Set targetFolder = fso.GetFolder("C:\")
Dim foundFile As Variant
For Each foundFile In targetFolder.Files
Debug.Print foundFile.Name
Next
End Sub
Section 25.6: Creating a FileSystemObject
Const ForReading = 1
Const ForWriting = 2
Const ForAppending = 8
Sub FsoExample()
Dim fso As Object ' declare variable
Set fso = CreateObject("Scripting.FileSystemObject") ' Set it to be a File System Object
' now use it to check if a file exists
Dim myFilePath As String
myFilePath = "C:\mypath\to\myfile.txt"
If fso.FileExists(myFilePath) Then
' do something
Else
' file doesn't exist
MsgBox "File doesn't exist"
End If
End Sub
Section 25.7: Reading a text file using a FileSystemObject
Const ForReading = 1
Const ForWriting = 2
Const ForAppending = 8
Sub ReadTextFileExample()
Dim fso As Object
Set fso = CreateObject("Scripting.FileSystemObject")
Dim sourceFile As Object
Dim myFilePath As String
Dim myFileText As String
myFilePath = "C:\mypath\to\myfile.txt"
GoalKicker.com – VBA Notes for Professionals 96
Set sourceFile = fso.OpenTextFile(myFilePath, ForReading)
myFileText = sourceFile.ReadAll ' myFileText now contains the content of the text file
sourceFile.Close ' close the file
' do whatever you might need to do with the text
' You can also read it line by line
Dim line As String
Set sourceFile = fso.OpenTextFile(myFilePath, ForReading)
While Not sourceFile.AtEndOfStream ' while we are not finished reading through the file
line = sourceFile.ReadLine
' do something with the line...
Wend
sourceFile.Close
End Sub
Section 25.8: Creating a text file with FileSystemObject
Sub CreateTextFileExample()
Dim fso As Object
Set fso = CreateObject("Scripting.FileSystemObject")
Dim targetFile As Object
Dim myFilePath As String
Dim myFileText As String
myFilePath = "C:\mypath\to\myfile.txt"
Set targetFile = fso.CreateTextFile(myFilePath, True) ' this will overwrite any existing file
targetFile.Write "This is some new text"
targetFile.Write " And this text will appear right after the first bit of text."
targetFile.WriteLine "This bit of text includes a newline character to ensure each write takes
its own line."
targetFile.Close ' close the file
End Sub
Section 25.9: Using FSO.BuildPath to build a Full Path from
folder path and file name
If you're accepting user input for folder paths, you might need to check for trailing backslashes (\) before building a
file path. The FSO.BuildPath method makes this simpler:
Const sourceFilePath As String = "C:\Temp" '<-- Without trailing backslash
Const targetFilePath As String = "C:\Temp\" '<-- With trailing backslash
Const fileName As String = "Results.txt"
Dim FSO As FileSystemObject
Set FSO = New FileSystemObject
Debug.Print FSO.BuildPath(sourceFilePath, fileName)
Debug.Print FSO.BuildPath(targetFilePath, fileName)
Output:
C:\Temp\Results.txt
C:\Temp\Results.txt
GoalKicker.com – VBA Notes for Professionals 97
Section 25.10: Writing to an existing file with FileSystemObject
Const ForReading = 1
Const ForWriting = 2
Const ForAppending = 8
Sub WriteTextFileExample()
Dim oFso
Set oFso = CreateObject("Scripting.FileSystemObject")
Dim oFile as Object
Dim myFilePath as String
Dim myFileText as String
myFilePath = "C:\mypath\to\myfile.txt"
' First check if the file exists
If oFso.FileExists(myFilePath) Then
' this will overwrite any existing filecontent with whatever you send the file
' to append data to the end of an existing file, use ForAppending instead
Set oFile = oFso.OpenTextFile(myFilePath, ForWriting)
Else
' create the file instead
Set oFile = oFso.CreateTextFile(myFilePath) ' skipping the optional boolean for overwrite if
exists as we already checked that the file doesn't exist.
End If
oFile.Write "This is some new text"
oFile.Write " And this text will appear right after the first bit of text."
oFile.WriteLine "This bit of text includes a newline character to ensure each write takes its
own line."
oFile.Close ' close the file
End Sub
GoalKicker.com – VBA Notes for Professionals 98
Chapter 26: Working With Files and
Directories Without Using
FileSystemObject
Section 26.1: Determining If Folders and Files Exist
Files:
To determine if a file exists, simply pass the filename to the Dir$ function and test to see if it returns a result. Note
that Dir$ supports wild-cards, so to test for a specific file, the passed pathName should to be tested to ensure that it
does not contain them. The sample below raises an error - if this isn't the desired behavior, the function can be
changed to simply return False.
Public Function FileExists(pathName As String) As Boolean
If InStr(1, pathName, "*") Or InStr(1, pathName, "?") Then
'Exit Function 'Return False on wild-cards.
Err.Raise 52 'Raise error on wild-cards.
End If
FileExists = Dir$(pathName) <> vbNullString
End Function
Folders (Dir$ method):
The Dir$() function can also be used to determine if a folder exists by specifying passing vbDirectory for the
optional attributes parameter. In this case, the passed pathName value must end with a path separator (\), as
matching filenames will cause false positives. Keep in mind that wild-cards are only allowed after the last path
separator, so the example function below will throw a run-time error 52 - "Bad file name or number" if the input
contains a wild-card. If this isn't the desired behavior, uncomment On Error Resume Next at the top of the
function. Also remember that Dir$ supports relative file paths (i.e. ..\Foo\Bar), so results are only guaranteed to
be valid as long as the current working directory is not changed.
Public Function FolderExists(ByVal pathName As String) As Boolean
'Uncomment the "On Error" line if paths with wild-cards should return False
'instead of raising an error.
'On Error Resume Next
If pathName = vbNullString Or Right$(pathName, 1) <> "\" Then
Exit Function
End If
FolderExists = Dir$(pathName, vbDirectory) <> vbNullString
End Function
Folders (ChDir method):
The ChDir statement can also be used to test if a folder exists. Note that this method will temporarily change the
environment that VBA is running in, so if that is a consideration, the Dir$ method should be used instead. It does
have the advantage of being much less forgiving with its parameter. This method also supports relative file paths,
so has the same caveat as the Dir$ method.
Public Function FolderExists(ByVal pathName As String) As Boolean
'Cache the current working directory
Dim cached As String
cached = CurDir$
On Error Resume Next
GoalKicker.com – VBA Notes for Professionals 99
ChDir pathName
FolderExists = Err.Number = 0
On Error GoTo 0
'Change back to the cached working directory.
ChDir cached
End Function
Section 26.2: Creating and Deleting File Folders
NOTE: For brevity, the examples below use the FolderExists function from the Determining If Folders and Files
Exist example in this topic.
The MkDir statement can be used to create a new folder. It accepts paths containing drive letters (C:\Foo), UNC
names (\\Server\Foo), relative paths (..\Foo), or the current working directory (Foo).
If the drive or UNC name is omitted (i.e. \Foo), the folder is created on the current drive. This may or may not be the
same drive as the current working directory.
Public Sub MakeNewDirectory(ByVal pathName As String)
'MkDir will fail if the directory already exists.
If FolderExists(pathName) Then Exit Sub
'This may still fail due to permissions, etc.
MkDir pathName
End Sub
The RmDir statement can be used to delete existing folders. It accepts paths in the same forms as MkDir and uses
the same relationship to the current working directory and drive. Note that the statement is similar to the Windows
rd shell command, so will throw a run-time error 75: "Path/File access error" if the target directory is not empty.
Public Sub DeleteDirectory(ByVal pathName As String)
If Right$(pathName, 1) <> "\" Then
pathName = pathName & "\"
End If
'Rmdir will fail if the directory doesn't exist.
If Not FolderExists(pathName) Then Exit Sub
'Rmdir will fail if the directory contains files.
If Dir$(pathName & "*") <> vbNullString Then Exit Sub
'Rmdir will fail if the directory contains directories.
Dim subDir As String
subDir = Dir$(pathName & "*", vbDirectory)
Do
If subDir <> "." And subDir <> ".." Then Exit Sub
subDir = Dir$(, vbDirectory)
Loop While subDir <> vbNullString
'This may still fail due to permissions, etc.
RmDir pathName
End Sub
GoalKicker.com – VBA Notes for Professionals 100
Chapter 27: Reading 2GB+ files in binary in
VBA and File Hashes
There is a built in easy way to read files in binary within VBA, however it has a restriction of 2GB (2,147,483,647
bytes - max of Long data type). As technology evolves, this 2GB limit is easily breached. e.g. an ISO image of
Operating System install DVD disc. Microsoft does provide a way to overcome this via low level Windows API and
here is a backup of it.
Also demonstrate (Read part) for calculating File Hashes without external program like fciv.exe from Microsoft.
Section 27.1: This have to be in a Class module, examples later
referred as "Random"
' How To Seek Past VBA's 2GB File Limit
' Source: https://support.microsoft.com/en-us/kb/189981 (Archived)
' This must be in a Class Module
Option Explicit
Public Enum W32F_Errors
W32F_UNKNOWN_ERROR = 45600
W32F_FILE_ALREADY_OPEN
W32F_PROBLEM_OPENING_FILE
W32F_FILE_ALREADY_CLOSED
W32F_Problem_seeking
End Enum
Private Const W32F_SOURCE = "Win32File Object"
Private Const GENERIC_WRITE = &H40000000
Private Const GENERIC_READ = &H80000000
Private Const FILE_ATTRIBUTE_NORMAL = &H80
Private Const CREATE_ALWAYS = 2
Private Const OPEN_ALWAYS = 4
Private Const INVALID_HANDLE_VALUE = -1
Private Const FILE_BEGIN = 0, FILE_CURRENT = 1, FILE_END = 2
Private Const FORMAT_MESSAGE_FROM_SYSTEM = &H1000
Private Declare Function FormatMessage Lib "kernel32" Alias "FormatMessageA" ( _
ByVal dwFlags As Long, _
lpSource As Long, _
ByVal dwMessageId As Long, _
ByVal dwLanguageId As Long, _
ByVal lpBuffer As String, _
ByVal nSize As Long, _
Arguments As Any) As Long
Private Declare Function ReadFile Lib "kernel32" ( _
ByVal hFile As Long, _
lpBuffer As Any, _
ByVal nNumberOfBytesToRead As Long, _
lpNumberOfBytesRead As Long, _
ByVal lpOverlapped As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function WriteFile Lib "kernel32" ( _
GoalKicker.com – VBA Notes for Professionals 101
ByVal hFile As Long, _
lpBuffer As Any, _
ByVal nNumberOfBytesToWrite As Long, _
lpNumberOfBytesWritten As Long, _
ByVal lpOverlapped As Long) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" ( _
ByVal lpFileName As String, _
ByVal dwDesiredAccess As Long, _
ByVal dwShareMode As Long, _
ByVal lpSecurityAttributes As Long, _
ByVal dwCreationDisposition As Long, _
ByVal dwFlagsAndAttributes As Long, _
ByVal hTemplateFile As Long) As Long
Private Declare Function SetFilePointer Lib "kernel32" ( _
ByVal hFile As Long, _
ByVal lDistanceToMove As Long, _
lpDistanceToMoveHigh As Long, _
ByVal dwMoveMethod As Long) As Long
Private Declare Function FlushFileBuffers Lib "kernel32" (ByVal hFile As Long) As Long
Private hFile As Long, sFName As String, fAutoFlush As Boolean
Public Property Get FileHandle() As Long
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
FileHandle = hFile
End Property
Public Property Get FileName() As String
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
FileName = sFName
End Property
Public Property Get IsOpen() As Boolean
IsOpen = hFile <> INVALID_HANDLE_VALUE
End Property
Public Property Get AutoFlush() As Boolean
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
AutoFlush = fAutoFlush
End Property
Public Property Let AutoFlush(ByVal NewVal As Boolean)
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
fAutoFlush = NewVal
End Property
Public Sub OpenFile(ByVal sFileName As String)
If hFile <> INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_OPEN, sFName
End If
hFile = CreateFile(sFileName, GENERIC_WRITE Or GENERIC_READ, 0, 0, OPEN_ALWAYS,
GoalKicker.com – VBA Notes for Professionals 102
FILE_ATTRIBUTE_NORMAL, 0)
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_PROBLEM_OPENING_FILE, sFileName
End If
sFName = sFileName
End Sub
Public Sub CloseFile()
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
CloseHandle hFile
sFName = ""
fAutoFlush = False
hFile = INVALID_HANDLE_VALUE
End Sub
Public Function ReadBytes(ByVal ByteCount As Long) As Variant
Dim BytesRead As Long, Bytes() As Byte
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
ReDim Bytes(0 To ByteCount - 1) As Byte
ReadFile hFile, Bytes(0), ByteCount, BytesRead, 0
ReadBytes = Bytes
End Function
Public Sub WriteBytes(DataBytes() As Byte)
Dim fSuccess As Long, BytesToWrite As Long, BytesWritten As Long
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
BytesToWrite = UBound(DataBytes) - LBound(DataBytes) + 1
fSuccess = WriteFile(hFile, DataBytes(LBound(DataBytes)), BytesToWrite, BytesWritten, 0)
If fAutoFlush Then Flush
End Sub
Public Sub Flush()
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
FlushFileBuffers hFile
End Sub
Public Sub SeekAbsolute(ByVal HighPos As Long, ByVal LowPos As Long)
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
LowPos = SetFilePointer(hFile, LowPos, HighPos, FILE_BEGIN)
End Sub
Public Sub SeekRelative(ByVal Offset As Long)
Dim TempLow As Long, TempErr As Long
If hFile = INVALID_HANDLE_VALUE Then
RaiseError W32F_FILE_ALREADY_CLOSED
End If
TempLow = SetFilePointer(hFile, Offset, ByVal 0&, FILE_CURRENT)
If TempLow = -1 Then
TempErr = Err.LastDllError
If TempErr Then
RaiseError W32F_Problem_seeking, "Error " & TempErr & "." & vbCrLf & CStr(TempErr)
End If
GoalKicker.com – VBA Notes for Professionals 103
End If
End Sub
Private Sub Class_Initialize()
hFile = INVALID_HANDLE_VALUE
End Sub
Private Sub Class_Terminate()
If hFile <> INVALID_HANDLE_VALUE Then CloseHandle hFile
End Sub
Private Sub RaiseError(ByVal ErrorCode As W32F_Errors, Optional sExtra)
Dim Win32Err As Long, Win32Text As String
Win32Err = Err.LastDllError
If Win32Err Then
Win32Text = vbCrLf & "Error " & Win32Err & vbCrLf & _
DecodeAPIErrors(Win32Err)
End If
Select Case ErrorCode
Case W32F_FILE_ALREADY_OPEN
Err.Raise W32F_FILE_ALREADY_OPEN, W32F_SOURCE, "The file '" & sExtra & "' is already
open." & Win32Text
Case W32F_PROBLEM_OPENING_FILE
Err.Raise W32F_PROBLEM_OPENING_FILE, W32F_SOURCE, "Error opening '" & sExtra & "'." &
Win32Text
Case W32F_FILE_ALREADY_CLOSED
Err.Raise W32F_FILE_ALREADY_CLOSED, W32F_SOURCE, "There is no open file."
Case W32F_Problem_seeking
Err.Raise W32F_Problem_seeking, W32F_SOURCE, "Seek Error." & vbCrLf & sExtra
Case Else
Err.Raise W32F_UNKNOWN_ERROR, W32F_SOURCE, "Unknown error." & Win32Text
End Select
End Sub
Private Function DecodeAPIErrors(ByVal ErrorCode As Long) As String
Dim sMessage As String, MessageLength As Long
sMessage = Space$(256)
MessageLength = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, 0&, ErrorCode, 0&, sMessage, 256&,
0&)
If MessageLength > 0 Then
DecodeAPIErrors = Left(sMessage, MessageLength)
Else
DecodeAPIErrors = "Unknown Error."
End If
End Function
Section 27.2: Code for Calculating File Hash in a Standard
module
Private Const HashTypeMD5 As String = "MD5" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.md5cryptoserviceprovider(v=vs.1
10).aspx
Private Const HashTypeSHA1 As String = "SHA1" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha1cryptoserviceprovider(v=vs.
110).aspx
Private Const HashTypeSHA256 As String = "SHA256" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha256cryptoserviceprovider(v=v
s.110).aspx
Private Const HashTypeSHA384 As String = "SHA384" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha384cryptoserviceprovider(v=v
s.110).aspx
GoalKicker.com – VBA Notes for Professionals 104
Private Const HashTypeSHA512 As String = "SHA512" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha512cryptoserviceprovider(v=v
s.110).aspx
Private uFileSize As Double ' Comment out if not testing performance by FileHashes()
Sub FileHashes()
Dim tStart As Date, tFinish As Date, sHash As String, aTestFiles As Variant, oTestFile As
Variant, aBlockSizes As Variant, oBlockSize As Variant
Dim BLOCKSIZE As Double
' This performs performance testing on different file sizes and block sizes
aBlockSizes = Array("2^12-1", "2^13-1", "2^14-1", "2^15-1", "2^16-1", "2^17-1", "2^18-1",
"2^19-1", "2^20-1", "2^21-1", "2^22-1", "2^23-1", "2^24-1", "2^25-1", "2^26-1")
aTestFiles = Array("C:\ISO\clonezilla-live-2.2.2-37-amd64.iso",
"C:\ISO\HPIP201.2014_0902.29.iso", "C:\ISO\SW_DVD5_Windows_Vista_Business_W32_32BIT_English.ISO",
"C:\ISO\Win10_1607_English_x64.iso",
"C:\ISO\SW_DVD9_Windows_Svr_Std_and_DataCtr_2012_R2_64Bit_English.ISO")
Debug.Print "Test files: " & Join(aTestFiles, " | ")
Debug.Print "BlockSizes: " & Join(aBlockSizes, " | ")
For Each oTestFile In aTestFiles
Debug.Print oTestFile
For Each oBlockSize In aBlockSizes
BLOCKSIZE = Evaluate(oBlockSize)
tStart = Now
sHash = GetFileHash(CStr(oTestFile), BLOCKSIZE, HashTypeMD5)
tFinish = Now
Debug.Print sHash, uFileSize, Format(tFinish - tStart, "hh:mm:ss"), oBlockSize & " (" &
BLOCKSIZE & ")"
Next
Next
End Sub
Private Function GetFileHash(ByVal sFile As String, ByVal uBlockSize As Double, ByVal sHashType As
String) As String
Dim oFSO As Object ' "Scripting.FileSystemObject"
Dim oCSP As Object ' One of the "CryptoServiceProvider"
Dim oRnd As Random ' "Random" Class by Microsoft, must be in the same file
Dim uBytesRead As Double, uBytesToRead As Double, bDone As Boolean
Dim aBlock() As Byte, aBytes As Variant ' Arrays to store bytes
Dim aHash() As Byte, sHash As String, i As Long
'Dim uFileSize As Double ' Un-Comment if GetFileHash() is to be used individually
Set oRnd = New Random ' Class by Microsoft: Random
Set oFSO = CreateObject("Scripting.FileSystemObject")
Set oCSP = CreateObject("System.Security.Cryptography." & sHashType & "CryptoServiceProvider")
If oFSO Is Nothing Or oRnd Is Nothing Or oCSP Is Nothing Then
MsgBox "One or more required objects cannot be created"
GoTo CleanUp
End If
uFileSize = oFSO.GetFile(sFile).Size ' FILELEN() has 2GB max!
uBytesRead = 0
bDone = False
sHash = String(oCSP.HashSize / 4, "0") ' Each hexadecimal has 4 bits
Application.ScreenUpdating = False
' Process the file in chunks of uBlockSize or less
If uFileSize = 0 Then
ReDim aBlock(0)
oCSP.TransformFinalBlock aBlock, 0, 0
GoalKicker.com – VBA Notes for Professionals 105
bDone = True
Else
With oRnd
.OpenFile sFile
Do
If uBytesRead + uBlockSize < uFileSize Then
uBytesToRead = uBlockSize
Else
uBytesToRead = uFileSize - uBytesRead
bDone = True
End If
' Read in some bytes
aBytes = .ReadBytes(uBytesToRead)
aBlock = aBytes
If bDone Then
oCSP.TransformFinalBlock aBlock, 0, uBytesToRead
uBytesRead = uBytesRead + uBytesToRead
Else
uBytesRead = uBytesRead + oCSP.TransformBlock(aBlock, 0, uBytesToRead, aBlock,
0)
End If
DoEvents
Loop Until bDone
.CloseFile
End With
End If
If bDone Then
' convert Hash byte array to an hexadecimal string
aHash = oCSP.hash
For i = 0 To UBound(aHash)
Mid$(sHash, i * 2 + (aHash(i) > 15) + 2) = Hex(aHash(i))
Next
End If
Application.ScreenUpdating = True
' Clean up
oCSP.Clear
CleanUp:
Set oFSO = Nothing
Set oRnd = Nothing
Set oCSP = Nothing
GetFileHash = sHash
End Function
The output is pretty interesting, my test files indicates that BLOCKSIZE = 131071 (2^17-1) gives overall
best performance with 32bit Office 2010 on Windows 7 x64, next best is 2^16-1 (65535). Note 2^27-1
yields Out of memory.
File Size (bytes) File Name
146,800,640 clonezilla-live-2.2.2-37-amd64.iso
798,210,048 HPIP201.2014_0902.29.iso
2,073,016,320 SW_DVD5_Windows_Vista_Business_W32_32BIT_English.ISO
4,380,387,328 Win10_1607_English_x64.iso
5,400,115,200 SW_DVD9_Windows_Svr_Std_and_DataCtr_2012_R2_64Bit_English.ISO
Section 27.3: Calculating all Files Hash from a root Folder
Another variation from the code above gives you more performance when you want to get hash codes of all files
GoalKicker.com – VBA Notes for Professionals 106
from a root folder including all sub folders.
Example of Worksheet:
Code
Option Explicit
Private Const HashTypeMD5 As String = "MD5" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.md5cryptoserviceprovider(v=vs.1
10).aspx
Private Const HashTypeSHA1 As String = "SHA1" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha1cryptoserviceprovider(v=vs.
110).aspx
Private Const HashTypeSHA256 As String = "SHA256" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha256cryptoserviceprovider(v=v
s.110).aspx
Private Const HashTypeSHA384 As String = "SHA384" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha384cryptoserviceprovider(v=v
s.110).aspx
Private Const HashTypeSHA512 As String = "SHA512" '
https://msdn.microsoft.com/en-us/library/system.security.cryptography.sha512cryptoserviceprovider(v=v
s.110).aspx
Private Const BLOCKSIZE As Double = 131071 ' 2^17-1
Private oFSO As Object
Private oCSP As Object
Private oRnd As Random ' Requires the Class from Microsoft
https://support.microsoft.com/en-us/kb/189981
Private sHashType As String
Private sRootFDR As String
Private oRng As Range
Private uFileCount As Double
Sub AllFileHashes() ' Active-X button calls this
Dim oWS As Worksheet
' | A: FileHash | B: FileSize | C: FileName | D: FilaName and Path | E: File Last Modification
Time | F: Time required to calculate has code (seconds)
With ThisWorkbook
' Clear All old entries on all worksheets
For Each oWS In .Worksheets
Set oRng = Intersect(oWS.UsedRange, oWS.UsedRange.Offset(2))
If Not oRng Is Nothing Then oRng.ClearContents
Next
With .Worksheets(1)
sHashType = Trim(.Range("A1").Value) ' Range(A1)
sRootFDR = Trim(.Range("C1").Value) ' Range(C1) Column B for file size
If Len(sHashType) = 0 Or Len(sRootFDR) = 0 Then Exit Sub
Set oRng = .Range("A3") ' First entry on First Page
End With
End With
uFileCount = 0
If oRnd Is Nothing Then Set oRnd = New Random ' Class by Microsoft: Random
If oFSO Is Nothing Then Set oFSO = CreateObject("Scripting.FileSystemObject") ' Just to get
correct FileSize
If oCSP Is Nothing Then Set oCSP = CreateObject("System.Security.Cryptography." & sHashType &
"CryptoServiceProvider")
GoalKicker.com – VBA Notes for Professionals 107
ProcessFolder oFSO.GetFolder(sRootFDR)
Application.StatusBar = False
Application.ScreenUpdating = True
oCSP.Clear
Set oCSP = Nothing
Set oRng = Nothing
Set oFSO = Nothing
Set oRnd = Nothing
Debug.Print "Total file count: " & uFileCount
End Sub
Private Sub ProcessFolder(ByRef oFDR As Object)
Dim oFile As Object, oSubFDR As Object, sHash As String, dStart As Date, dFinish As Date
Application.ScreenUpdating = False
For Each oFile In oFDR.Files
uFileCount = uFileCount + 1
Application.StatusBar = uFileCount & ": " & Right(oFile.Path, 255 - Len(uFileCount) - 2)
oCSP.Initialize ' Reinitialize the CryptoServiceProvider
dStart = Now
sHash = GetFileHash(oFile, BLOCKSIZE, sHashType)
dFinish = Now
With oRng
.Value = sHash
.Offset(0, 1).Value = oFile.Size ' File Size in bytes
.Offset(0, 2).Value = oFile.Name ' File name with extension
.Offset(0, 3).Value = oFile.Path ' Full File name and Path
.Offset(0, 4).Value = FileDateTime(oFile.Path) ' Last modification timestamp of file
.Offset(0, 5).Value = dFinish - dStart ' Time required to calculate hash code
End With
If oRng.Row = Rows.Count Then
' Max rows reached, start on Next sheet
If oRng.Worksheet.Index + 1 > ThisWorkbook.Worksheets.Count Then
MsgBox "All rows in all worksheets have been used, please create more sheets"
End
End If
Set oRng = ThisWorkbook.Sheets(oRng.Worksheet.Index + 1).Range("A3")
oRng.Worksheet.Activate
Else
' Move to next row otherwise
Set oRng = oRng.Offset(1)
End If
Next
'Application.StatusBar = False
Application.ScreenUpdating = True
oRng.Activate
For Each oSubFDR In oFDR.SubFolders
ProcessFolder oSubFDR
Next
End Sub
Private Function GetFileHash(ByVal sFile As String, ByVal uBlockSize As Double, ByVal sHashType As
String) As String
Dim uBytesRead As Double, uBytesToRead As Double, bDone As Boolean
Dim aBlock() As Byte, aBytes As Variant ' Arrays to store bytes
Dim aHash() As Byte, sHash As String, i As Long, oTmp As Variant
Dim uFileSize As Double ' Un-Comment if GetFileHash() is to be used individually
If oRnd Is Nothing Then Set oRnd = New Random ' Class by Microsoft: Random
If oFSO Is Nothing Then Set oFSO = CreateObject("Scripting.FileSystemObject") ' Just to get
correct FileSize
If oCSP Is Nothing Then Set oCSP = CreateObject("System.Security.Cryptography." & sHashType &
GoalKicker.com – VBA Notes for Professionals 108
"CryptoServiceProvider")
If oFSO Is Nothing Or oRnd Is Nothing Or oCSP Is Nothing Then
MsgBox "One or more required objects cannot be created"
Exit Function
End If
uFileSize = oFSO.GetFile(sFile).Size ' FILELEN() has 2GB max
uBytesRead = 0
bDone = False
sHash = String(oCSP.HashSize / 4, "0") ' Each hexadecimal is 4 bits
' Process the file in chunks of uBlockSize or less
If uFileSize = 0 Then
ReDim aBlock(0)
oCSP.TransformFinalBlock aBlock, 0, 0
bDone = True
Else
With oRnd
On Error GoTo CannotOpenFile
.OpenFile sFile
Do
If uBytesRead + uBlockSize < uFileSize Then
uBytesToRead = uBlockSize
Else
uBytesToRead = uFileSize - uBytesRead
bDone = True
End If
' Read in some bytes
aBytes = .ReadBytes(uBytesToRead)
aBlock = aBytes
If bDone Then
oCSP.TransformFinalBlock aBlock, 0, uBytesToRead
uBytesRead = uBytesRead + uBytesToRead
Else
uBytesRead = uBytesRead + oCSP.TransformBlock(aBlock, 0, uBytesToRead, aBlock,
0)
End If
DoEvents
Loop Until bDone
.CloseFile
CannotOpenFile:
If Err.Number <> 0 Then ' Change the hash code to the Error description
oTmp = Split(Err.Description, vbCrLf)
sHash = oTmp(1) & ":" & oTmp(2)
End If
End With
End If
If bDone Then
' convert Hash byte array to an hexadecimal string
aHash = oCSP.hash
For i = 0 To UBound(aHash)
Mid$(sHash, i * 2 + (aHash(i) > 15) + 2) = Hex(aHash(i))
Next
End If
GetFileHash = sHash
End Function
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Chapter 28: Creating a procedure
Section 28.1: Introduction to procedures
A Sub is a procedure that performs a specific task but does not return a specific value.
Sub ProcedureName ([argument_list])
[statements]
End Sub
If no access modifier is specified, a procedure is Public by default.
A Function is a procedure that is given data and returns a value, ideally without global or module-scope sideeffects.
Function ProcedureName ([argument_list]) [As ReturnType]
[statements]
End Function
A Property is a procedure that encapsulates module data. A property can have up to 3 accessors: Get to return a
value or object reference, Let to assign a value, and/or Set to assign an object reference.
Property Get|Let|Set PropertyName([argument_list]) [As ReturnType]
[statements]
End Property
Properties are usually used in class modules (although they are allowed in standard modules as well), exposing
accessor to data that is otherwise inaccessible to the calling code. A property that only exposes a Get accessor is
"read-only"; a property that would only expose a Let and/or Set accessor is "write-only". Write-only properties are
not considered a good programming practice - if the client code can write a value, it should be able to read it back.
Consider implementing a Sub procedure instead of making a write-only property.
Returning a value
A Function or Property Get procedure can (and should!) return a value to its caller. This is done by assigning the
identifier of the procedure:
Property Get Foo() As Integer
Foo = 42
End Property
Section 28.2: Function With Examples
As stated above Functions are smaller procedures that contain small pieces of code which may be repetitive inside
a Procedure.
Functions are used to reduce redundancy in code.
Similar to a Procedure, A function can be declared with or without an arguments list.
Function is declared as a return type, as all functions return a value. The Name and the Return Variable of a
function are the Same.
GoalKicker.com – VBA Notes for Professionals 110
1. Function With Parameter:
Function check_even(i as integer) as boolean
if (i mod 2) = 0 then
check_even = True
else
check_even=False
end if
end Function
2. Function Without Parameter:
Function greet() as String
greet= "Hello Coder!"
end Function
The Function can be called in various ways inside a function. Since a Function declared with a return type is
basically a variable. it is used similar to a variable.
Functional Calls:
call greet() 'Similar to a Procedural call just allows the Procedure to use the
'variable greet
string_1=greet() 'The Return value of the function is used for variable
'assignment
Further the function can also be used as conditions for if and other conditional statements.
for i = 1 to 10
if check_even(i) then
msgbox i & " is Even"
else
msgbox i & " is Odd"
end if
next i
Further more Functions can have modifiers such as By ref and By val for their arguments.
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Chapter 29: Procedure Calls
Parameter Info
IdentifierName The name of the procedure to call.
arguments A comma-separated list of arguments to be passed to the procedure.
Section 29.1: This is confusing. Why not just always use
parentheses?
Parentheses are used to enclose the arguments of function calls. Using them for procedure calls can cause
unexpected problems.
Because they can introduce bugs, both at run-time by passing a possibly unintended value to the procedure, and at
compile-time by simply being invalid syntax.
Run-time
Redundant parentheses can introduce bugs. Given a procedure that takes an object reference as a parameter...
Sub DoSomething(ByRef target As Range)
End Sub
...and called with parentheses:
DoSomething (Application.ActiveCell) 'raises an error at runtime
This will raise an "Object Required" runtime error #424. Other errors are possible in other circumstances: here the
Application.ActiveCell Range object reference is being evaluated and passed by value regardless of the
procedure's signature specifying that target would be passed ByRef. The actual value passed ByVal to DoSomething
in the above snippet, is Application.ActiveCell.Value.
Parentheses force VBA to evaluate the value of the bracketed expression, and pass the result ByVal to the called
procedure. When the type of the evaluated result mismatches the procedure's expected type and cannot be
implicitly converted, a runtime error is raised.
Compile-time
This code will fail to compile:
MsgBox ("Invalid Code!", vbCritical)
Because the expression ("Invalid Code!", vbCritical) cannot be evaluated to a value.
This would compile and work:
MsgBox ("Invalid Code!"), (vbCritical)
But would definitely look silly. Avoid redundant parentheses.
Section 29.2: Implicit Call Syntax
ProcedureName
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ProcedureName argument1, argument2
Call a procedure by its name without any parentheses.
Edge case
The Call keyword is only required in one edge case:
Call DoSomething : DoSomethingElse
DoSomething and DoSomethingElse are procedures being called. If the Call keyword was removed, then
DoSomething would be parsed as a line label rather than a procedure call, which would break the code:
DoSomething: DoSomethingElse 'only DoSomethingElse will run
Section 29.3: Optional Arguments
Some procedures have optional arguments. Optional arguments always come after required arguments, but the
procedure can be called without them.
For example, if the function, ProcedureName were to have two required arguments (argument1, argument2), and one
optional argument, optArgument3, it could be called at least four ways:
' Without optional argument
result = ProcedureName("A", "B")
' With optional argument
result = ProcedureName("A", "B", "C")
' Using named arguments (allows a different order)
result = ProcedureName(optArgument3:="C", argument1:="A", argument2:="B")
' Mixing named and unnamed arguments
result = ProcedureName("A", "B", optArgument3:="C")
The structure of the function header being called here would look something like this:
Function ProcedureName(argument1 As String, argument2 As String, Optional optArgument3 As String)
As String
The Optional keyword indicates that this argument can be omitted. As mentioned before - any optional arguments
introduced in the header must appear at the end, after any required arguments.
You can also provide a default value for the argument in the case that a value isn't passed to the function:
Function ProcedureName(argument1 As String, argument2 As String, Optional optArgument3 As String =
"C") As String
In this function, if the argument for c isn't supplied it's value will default to "C". If a value is supplied then this will
override the default value.
Section 29.4: Explicit Call Syntax
Call ProcedureName
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Call ProcedureName(argument1, argument2)
The explicit call syntax requires the Call keyword and parentheses around the argument list; parentheses are
redundant if there are no parameters. This syntax was made obsolete when the more modern implicit call syntax
was added to VB.
Section 29.5: Return Values
To retrieve the result of a procedure call (e.g. Function or Property Get procedures), put the call on the right-hand
side of an assignment:
result = ProcedureName
result = ProcedureName(argument1, argument2)
Parentheses must be present if there are parameters. If the procedure has no parameters, the parentheses are
redundant.
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Chapter 30: Conditional Compilation
Section 30.1: Changing code behavior at compile time
The #Const directive is used to define a custom preprocessor constant. These can later be used by #If to control
which blocks of code get compiled and executed.
#Const DEBUGMODE = 1
#If DEBUGMODE Then
Const filepath As String = "C:\Users\UserName\Path\To\File.txt"
#Else
Const filepath As String = "\\server\share\path\to\file.txt"
#End If
This results in the value of filepath being set to "C:\Users\UserName\Path\To\File.txt". Removing the #Const
line, or changing it to #Const DEBUGMODE = 0 would result in the filepath being set to
"\\server\share\path\to\file.txt".
#Const Scope
The #Const directive is only effective for a single code file (module or class). It must be declared for each and every
file you wish to use your custom constant in. Alternatively, you can declare a #Const globally for your project by
going to Tools >> [Your Project Name] Project Properties. This will bring up the project properties dialog box where
we’ll enter the constant declaration. In the “Conditional Compilation Arguments” box, type in [constName] =
[value]. You can enter more than 1 constant by separating them with a colon, like [constName1] = [value1] :
[constName2] = [value2].
Pre-defined Constants
Some compilation constants are already pre-defined. Which ones exist will depend on the bitness of the office
version you're running VBA in. Note that Vba7 was introduced alongside Office 2010 to support 64 bit versions of
Office.
GoalKicker.com – VBA Notes for Professionals 115
Constant 16 bit 32 bit 64 bit
Vba6 False If Vba6 False
Vba7 False If Vba7 True
Win16 True False False
Win32 False True True
Win64 False False True
Mac False If Mac If Mac
Note that Win64/Win32 refer to the Office version, not the Windows version. For example Win32 = TRUE in 32-bit
Office, even if the OS is a 64-bit version of Windows.
Section 30.2: Using Declare Imports that work on all versions
of Oce
#If Vba7 Then
' It's important to check for Win64 first,
' because Win32 will also return true when Win64 does.
#If Win64 Then
Declare PtrSafe Function GetFoo64 Lib "exampleLib32" () As LongLong
#Else
Declare PtrSafe Function GetFoo Lib "exampleLib32" () As Long
#End If
#Else
' Must be Vba6, the PtrSafe keyword didn't exist back then,
' so we need to declare Win32 imports a bit differently than above.
#If Win32 Then
Declare Function GetFoo Lib "exampleLib32"() As Long
#Else
Declare Function GetFoo Lib "exampleLib"() As Integer
#End If
#End If
This can be simplified a bit depending on what versions of office you need to support. For example, not many
people are still supporting 16 bit versions of Office. The last version of 16 bit office was version 4.3, released in
1994, so the following declaration is sufficient for nearly all modern cases (including Office 2007).
#If Vba7 Then
' It's important to check for Win64 first,
' because Win32 will also return true when Win64 does.
#If Win64 Then
Declare PtrSafe Function GetFoo64 Lib "exampleLib32" () As LongLong
#Else
Declare PtrSafe Function GetFoo Lib "exampleLib32" () As Long
#End If
#Else
' Must be Vba6. We don't support 16 bit office, so must be Win32.
Declare Function GetFoo Lib "exampleLib32"() As Long
#End If
If you don't have to support anything older than Office 2010, this declaration works just fine.
' We only have 2010 installs, so we already know we have Vba7.
GoalKicker.com – VBA Notes for Professionals 116
#If Win64 Then
Declare PtrSafe Function GetFoo64 Lib "exampleLib32" () As LongLong
#Else
Declare PtrSafe Function GetFoo Lib "exampleLib32" () As Long
#End If
GoalKicker.com – VBA Notes for Professionals 117
Chapter 31: Object-Oriented VBA
Section 31.1: Abstraction
Abstraction levels help determine when to split things up.
Abstraction is achieved by implementing functionality with increasingly detailed code. The entry point of a macro
should be a small procedure with a high abstraction level that makes it easy to grasp at a glance what's going on:
Public Sub DoSomething()
With New SomeForm
Set .Model = CreateViewModel
.Show vbModal
If .IsCancelled Then Exit Sub
ProcessUserData .Model
End With
End Sub
The DoSomething procedure has a high abstraction level: we can tell that it's displaying a form and creating some
model, and passing that object to some ProcessUserData procedure that knows what to do with it - how the model
is created is the job of another procedure:
Private Function CreateViewModel() As ISomeModel
Dim result As ISomeModel
Set result = SomeModel.Create(Now, Environ$("UserName"))
result.AvailableItems = GetAvailableItems
Set CreateViewModel = result
End Function
The CreateViewModel function is only responsible for creating some ISomeModel instance. Part of that responsibility
is to acquire an array of available items - how these items are acquired is an implementation detail that's abstracted
behind the GetAvailableItems procedure:
Private Function GetAvailableItems() As Variant
GetAvailableItems = DataSheet.Names("AvailableItems").RefersToRange
End Function
Here the procedure is reading the available values from a named range on a DataSheet worksheet. It could just as
well be reading them from a database, or the values could be hard-coded: it's an implementation detail that's none
of a concern for any of the higher abstraction levels.
Section 31.2: Encapsulation
Encapsulation hides implementation details from client code.
The Handling QueryClose example demonstrates encapsulation: the form has a checkbox control, but its client
code doesn't work with it directly - the checkbox is an implementation detail, what the client code needs to know is
whether the setting is enabled or not.
When the checkbox value changes, the handler assigns a private field member:
Private Type TView
IsCancelled As Boolean
SomeOtherSetting As Boolean
'other properties skipped for brievety
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End Type
Private this As TView
'...
Private Sub SomeOtherSettingInput_Change()
this.SomeOtherSetting = CBool(SomeOtherSettingInput.Value)
End Sub
And when the client code wants to read that value, it doesn't need to worry about a checkbox - instead it simply
uses the SomeOtherSetting property:
Public Property Get SomeOtherSetting() As Boolean
SomeOtherSetting = this.SomeOtherSetting
End Property
The SomeOtherSetting property encapsulates the checkbox' state; client code doesn't need to know that there's a
checkbox involved, only that there's a setting with a Boolean value. By encapsulating the Boolean value, we've added
an abstraction layer around the checkbox.
Using interfaces to enforce immutability
Let's push that a step further by encapsulating the form's model in a dedicated class module. But if we made a
Public Property for the UserName and Timestamp, we would have to expose Property Let accessors, making the
properties mutable, and we don't want the client code to have the ability to change these values after they're set.
The CreateViewModel function in the Abstraction example returns an ISomeModel class: that's our interface, and it
looks something like this:
Option Explicit
Public Property Get Timestamp() As Date
End Property
Public Property Get UserName() As String
End Property
Public Property Get AvailableItems() As Variant
End Property
Public Property Let AvailableItems(ByRef value As Variant)
End Property
Public Property Get SomeSetting() As String
End Property
Public Property Let SomeSetting(ByVal value As String)
End Property
Public Property Get SomeOtherSetting() As Boolean
End Property
Public Property Let SomeOtherSetting(ByVal value As Boolean)
End Property
Notice Timestamp and UserName properties only expose a Property Get accessor. Now the SomeModel class can
implement that interface:
GoalKicker.com – VBA Notes for Professionals 119
Option Explicit
Implements ISomeModel
Private Type TModel
Timestamp As Date
UserName As String
SomeSetting As String
SomeOtherSetting As Boolean
AvailableItems As Variant
End Type
Private this As TModel
Private Property Get ISomeModel_Timestamp() As Date
ISomeModel_Timestamp = this.Timestamp
End Property
Private Property Get ISomeModel_UserName() As String
ISomeModel_UserName = this.UserName
End Property
Private Property Get ISomeModel_AvailableItems() As Variant
ISomeModel_AvailableItems = this.AvailableItems
End Property
Private Property Let ISomeModel_AvailableItems(ByRef value As Variant)
this.AvailableItems = value
End Property
Private Property Get ISomeModel_SomeSetting() As String
ISomeModel_SomeSetting = this.SomeSetting
End Property
Private Property Let ISomeModel_SomeSetting(ByVal value As String)
this.SomeSetting = value
End Property
Private Property Get ISomeModel_SomeOtherSetting() As Boolean
ISomeModel_SomeOtherSetting = this.SomeOtherSetting
End Property
Private Property Let ISomeModel_SomeOtherSetting(ByVal value As Boolean)
this.SomeOtherSetting = value
End Property
Public Property Get Timestamp() As Date
Timestamp = this.Timestamp
End Property
Public Property Let Timestamp(ByVal value As Date)
this.Timestamp = value
End Property
Public Property Get UserName() As String
UserName = this.UserName
End Property
Public Property Let UserName(ByVal value As String)
this.UserName = value
End Property
Public Property Get AvailableItems() As Variant
AvailableItems = this.AvailableItems
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End Property
Public Property Let AvailableItems(ByRef value As Variant)
this.AvailableItems = value
End Property
Public Property Get SomeSetting() As String
SomeSetting = this.SomeSetting
End Property
Public Property Let SomeSetting(ByVal value As String)
this.SomeSetting = value
End Property
Public Property Get SomeOtherSetting() As Boolean
SomeOtherSetting = this.SomeOtherSetting
End Property
Public Property Let SomeOtherSetting(ByVal value As Boolean)
this.SomeOtherSetting = value
End Property
The interface members are all Private, and all members of the interface must be implemented for the code to
compile. The Public members are not part of the interface, and are therefore not exposed to code written against
the ISomeModel interface.
Using a Factory Method to simulate a constructor
Using a VB_PredeclaredId attribute, we can make the SomeModel class have a default instance, and write a function
that works like a type-level (Shared in VB.NET, static in C#) member that the client code can call without needing to
first create an instance, like we did here:
Private Function CreateViewModel() As ISomeModel
Dim result As ISomeModel
Set result = SomeModel.Create(Now, Environ$("UserName"))
result.AvailableItems = GetAvailableItems
Set CreateViewModel = result
End Function
This factory method assigns the property values that are read-only when accessed from the ISomeModel interface,
here Timestamp and UserName:
Public Function Create(ByVal pTimeStamp As Date, ByVal pUserName As String) As ISomeModel
With New SomeModel
.Timestamp = pTimeStamp
.UserName = pUserName
Set Create = .Self
End With
End Function
Public Property Get Self() As ISomeModel
Set Self = Me
End Property
And now we can code against the ISomeModel interface, which exposes Timestamp and UserName as read-only
properties that can never be reassigned (as long as the code is written against the interface).
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Section 31.3: Polymorphism
Polymorphism is the ability to present the same interface for different underlying implementations.
The ability to implement interfaces allows completely decoupling the application logic from the UI, or from the
database, or from this or that worksheet.
Say you have an ISomeView interface that the form itself implements:
Option Explicit
Public Property Get IsCancelled() As Boolean
End Property
Public Property Get Model() As ISomeModel
End Property
Public Property Set Model(ByVal value As ISomeModel)
End Property
Public Sub Show()
End Sub
The form's code-behind could look like this:
Option Explicit
Implements ISomeView
Private Type TView
IsCancelled As Boolean
Model As ISomeModel
End Type
Private this As TView
Private Property Get ISomeView_IsCancelled() As Boolean
ISomeView_IsCancelled = this.IsCancelled
End Property
Private Property Get ISomeView_Model() As ISomeModel
Set ISomeView_Model = this.Model
End Property
Private Property Set ISomeView_Model(ByVal value As ISomeModel)
Set this.Model = value
End Property
Private Sub ISomeView_Show()
Me.Show vbModal
End Sub
Private Sub SomeOtherSettingInput_Change()
this.Model.SomeOtherSetting = CBool(SomeOtherSettingInput.Value)
End Sub
'...other event handlers...
Private Sub OkButton_Click()
Me.Hide
End Sub
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Private Sub CancelButton_Click()
this.IsCancelled = True
Me.Hide
End Sub
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
If CloseMode = VbQueryClose.vbFormControlMenu Then
Cancel = True
this.IsCancelled = True
Me.Hide
End If
End Sub
But then, nothing forbids creating another class module that implements the ISomeView interface without being a
user form - this could be a SomeViewMock class:
Option Explicit
Implements ISomeView
Private Type TView
IsCancelled As Boolean
Model As ISomeModel
End Type
Private this As TView
Public Property Get IsCancelled() As Boolean
IsCancelled = this.IsCancelled
End Property
Public Property Let IsCancelled(ByVal value As Boolean)
this.IsCancelled = value
End Property
Private Property Get ISomeView_IsCancelled() As Boolean
ISomeView_IsCancelled = this.IsCancelled
End Property
Private Property Get ISomeView_Model() As ISomeModel
Set ISomeView_Model = this.Model
End Property
Private Property Set ISomeView_Model(ByVal value As ISomeModel)
Set this.Model = value
End Property
Private Sub ISomeView_Show()
'do nothing
End Sub
And now we can change the code that works with a UserForm and make it work off the ISomeView interface, e.g. by
giving it the form as a parameter instead of instantiating it:
Public Sub DoSomething(ByVal view As ISomeView)
With view
Set .Model = CreateViewModel
.Show
If .IsCancelled Then Exit Sub
ProcessUserData .Model
End With
End Sub
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Because the DoSomething method depends on an interface (i.e. an abstraction) and not a concrete class (e.g. a
specific UserForm), we can write an automated unit test that ensures that ProcessUserData isn't executed when
view.IsCancelled is True, by making our test create a SomeViewMock instance, setting its IsCancelled property to
True, and passing it to DoSomething.
Testable code depends on abstractions
Writing unit tests in VBA can be done, there are add-ins out there that even integrate it into the IDE. But when code
is tightly coupled with a worksheet, a database, a form, or the file system, then the unit test starts requiring an actual
worksheet, database, form, or file system - and these dependencies are new out-of-control failure points that
testable code should isolate, so that unit tests don't require an actual worksheet, database, form, or file system.
By writing code against interfaces, in a way that allows test code to inject stub/mock implementations (like the
above SomeViewMock example), you can write tests in a "controlled environment", and simulate what happens when
every single one of the 42 possible permutations of user interactions on the form's data, without even once
displaying a form and manually clicking on a form control.
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Chapter 32: Creating a Custom Class
Section 32.1: Adding a Property to a Class
A Property procedure is a series of statement that retrieves or modifies a custom property on a module.
There are three types of property accessors:
1. A Get procedure that returns the value of a property.
2. A Let procedure that assigns a (non-Object) value to an object.
3. A Set procedure that assigns an Object reference.
Property accessors are often defined in pairs, using both a Get and Let/Set for each property. A property with only
a Get procedure would be read-only, while a property with only a Let/Set procedure would be write-only.
In the following example, four property accessors are defined for the DateRange class:
1. StartDate (read/write). Date value representing the earlier date in a range. Each procedure uses the value of
the module variable, mStartDate.
2. EndDate (read/write). Date value representing the later date in a range. Each procedure uses the value of the
module variable, mEndDate.
3. DaysBetween (read-only). Calculated Integer value representing the number of days between the two dates.
Because there is only a Get procedure, this property cannot be modified directly.
4. RangeToCopy (write-only). A Set procedure used to copy the values of an existing DateRange object.
Private mStartDate As Date ' Module variable to hold the starting date
Private mEndDate As Date ' Module variable to hold the ending date
' Return the current value of the starting date
Public Property Get StartDate() As Date
StartDate = mStartDate
End Property
' Set the starting date value. Note that two methods have the name StartDate
Public Property Let StartDate(ByVal NewValue As Date)
mStartDate = NewValue
End Property
' Same thing, but for the ending date
Public Property Get EndDate() As Date
EndDate = mEndDate
End Property
Public Property Let EndDate(ByVal NewValue As Date)
mEndDate = NewValue
End Property
' Read-only property that returns the number of days between the two dates
Public Property Get DaysBetween() As Integer
DaysBetween = DateDiff("d", mStartDate, mEndDate)
End Function
' Write-only property that passes an object reference of a range to clone
Public Property Set RangeToCopy(ByRef ExistingRange As DateRange)
Me.StartDate = ExistingRange.StartDate
Me.EndDate = ExistingRange.EndDate
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End Property
Section 32.2: Class module scope, instancing and re-use
By default, a new class module is a Private class, so it is only available for instantiation and use within the VBProject
in which it is defined. You can declare, instantiate and use the class anywhere in the same project:
'Class List has Instancing set to Private
'In any other module in the SAME project, you can use:
Dim items As List
Set items = New List
But often you'll write classes that you'd like to use in other projects without copying the module between projects. If
you define a class called List in ProjectA, and want to use that class in ProjectB, then you'll need to perform 4
actions:
1. Change the instancing property of the List class in ProjectA in the Properties window, from Private to
PublicNotCreatable
2. Create a public "factory" function in ProjectA that creates and returns an instance of a List class. Typically
the factory function would include arguments for the initialization of the class instance. The factory function
is required because the class can be used by ProjectB but ProjectB cannot directly create an instance of
ProjectA's class.
Public Function CreateList(ParamArray values() As Variant) As List
Dim tempList As List
Dim itemCounter As Long
Set tempList = New List
For itemCounter = LBound(values) to UBound(values)
tempList.Add values(itemCounter)
Next itemCounter
Set CreateList = tempList
End Function
3. In ProjectB add a reference to ProjectA using the Tools..References... menu.
4. In ProjectB, declare a variable and assign it an instance of List using the factory function from ProjectA
Dim items As ProjectA.List
Set items = ProjectA.CreateList("foo","bar")
'Use the items list methods and properties
items.Add "fizz"
Debug.Print items.ToString()
'Destroy the items object
Set items = Nothing
Section 32.3: Adding Functionality to a Class
Any public Sub, Function, or Property inside a class module can be called by preceding the call with an object
reference:
Object.Procedure
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In a DateRange class, a Sub could be used to add a number of days to the end date:
Public Sub AddDays(ByVal NoDays As Integer)
mEndDate = mEndDate + NoDays
End Sub
A Function could return the last day of the next month-end (note that GetFirstDayOfMonth would not be visible
outside the class because it is private):
Public Function GetNextMonthEndDate() As Date
GetNextMonthEndDate = DateAdd("m", 1, GetFirstDayOfMonth())
End Function
Private Function GetFirstDayOfMonth() As Date
GetFirstDayOfMonth = DateAdd("d", -DatePart("d", mEndDate), mEndDate)
End Function
Procedures can accept arguments of any type, including references to objects of the class being defined.
The following example tests whether the current DateRange object has a starting date and ending date that includes
the starting and ending date of another DateRange object.
Public Function ContainsRange(ByRef TheRange As DateRange) As Boolean
ContainsRange = TheRange.StartDate >= Me.StartDate And TheRange.EndDate <= Me.EndDate
End Function
Note the use of the Me notation as a way to access the value of the object running the code.
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Chapter 33: Interfaces
An Interface is a way to define a set of behaviors that a class will perform. The definition of an interface is a list of
method signatures (name, parameters, and return type). A class having all of the methods is said to "implement"
that interface.
In VBA, using interfaces lets the compiler check that a module implements all of its methods. A variable or
parameter can be defined in terms of an interface instead of a specific class.
Section 33.1: Multiple Interfaces in One Class - Flyable and
Swimable
Using the Flyable example as a starting point, we can add a second interface, Swimmable, with the following code:
Sub Swim()
' No code
End Sub
The Duck object can Implement both flying and swimming:
Implements Flyable
Implements Swimmable
Public Sub Flyable_Fly()
Debug.Print "Flying With Wings!"
End Sub
Public Function Flyable_GetAltitude() As Long
Flyable_GetAltitude = 30
End Function
Public Sub Swimmable_Swim()
Debug.Print "Floating on the water"
End Sub
A Fish class can implement Swimmable, too:
Implements Swimmable
Public Sub Swimmable_Swim()
Debug.Print "Swimming under the water"
End Sub
Now, we can see that the Duck object can be passed to a Sub as a Flyable on one hand, and a Swimmable on the
other:
Sub InterfaceTest()
Dim MyDuck As New Duck
Dim MyAirplane As New Airplane
Dim MyFish As New Fish
Debug.Print "Fly Check..."
FlyAndCheckAltitude MyDuck
FlyAndCheckAltitude MyAirplane
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Debug.Print "Swim Check..."
TrySwimming MyDuck
TrySwimming MyFish
End Sub
Public Sub FlyAndCheckAltitude(F As Flyable)
F.Fly
Debug.Print F.GetAltitude
End Sub
Public Sub TrySwimming(S As Swimmable)
S.Swim
End Sub
The output of this code is:
Fly Check...
Flying With Wings!
30
Flying With Jet Engines!
10000
Swim Check...
Floating on the water
Swimming under the water
Section 33.2: Simple Interface - Flyable
The interface Flyable is a class module with the following code:
Public Sub Fly()
' No code.
End Sub
Public Function GetAltitude() As Long
' No code.
End Function
A class module, Airplane, uses the Implements keyword to tell the compiler to raise an error unless it has two
methods: a Flyable_Fly() sub and a Flyable_GetAltitude() function that returns a Long.
Implements Flyable
Public Sub Flyable_Fly()
Debug.Print "Flying With Jet Engines!"
End Sub
Public Function Flyable_GetAltitude() As Long
Flyable_GetAltitude = 10000
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End Function
A second class module, Duck, also implements Flyable:
Implements Flyable
Public Sub Flyable_Fly()
Debug.Print "Flying With Wings!"
End Sub
Public Function Flyable_GetAltitude() As Long
Flyable_GetAltitude = 30
End Function
We can write a routine that accepts any Flyable value, knowing that it will respond to a command of Fly or
GetAltitude:
Public Sub FlyAndCheckAltitude(F As Flyable)
F.Fly
Debug.Print F.GetAltitude
End Sub
Because the interface is defined, the IntelliSense popup window will show Fly and GetAltitude for F.
When we run the following code:
Dim MyDuck As New Duck
Dim MyAirplane As New Airplane
FlyAndCheckAltitude MyDuck
FlyAndCheckAltitude MyAirplane
The output is:
Flying With Wings!
30
Flying With Jet Engines!
10000
Note that even though the subroutine is named Flyable_Fly in both Airplane and Duck, it can be called as Fly
when the variable or parameter is defined as Flyable. If the variable is defined specifically as a Duck, it would have
to be called as Flyable_Fly.
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Chapter 34: Recursion
A function that calls itself is said to be recursive. Recursive logic can often be implemented as a loop, too. Recursion
must be controlled with a parameter, so that the function knows when to stop recursing and deepening the call
stack. Infinite recursion eventually causes a run-time error '28': "Out of stack space".
See Recursion.
Section 34.1: Factorials
Function Factorial(Value As Long) As Long
If Value = 0 Or Value = 1 Then
Factorial = 1
Else
Factorial = Factorial(Value - 1) * Value
End If
End Function
Section 34.2: Folder Recursion
Early Bound (with a reference to Microsoft Scripting Runtime)
Sub EnumerateFilesAndFolders( _
FolderPath As String, _
Optional MaxDepth As Long = -1, _
Optional CurrentDepth As Long = 0, _
Optional Indentation As Long = 2)
Dim FSO As Scripting.FileSystemObject
Set FSO = New Scripting.FileSystemObject
'Check the folder exists
If FSO.FolderExists(FolderPath) Then
Dim fldr As Scripting.Folder
Set fldr = FSO.GetFolder(FolderPath)
'Output the starting directory path
If CurrentDepth = 0 Then
Debug.Print fldr.Path
End If
'Enumerate the subfolders
Dim subFldr As Scripting.Folder
For Each subFldr In fldr.SubFolders
Debug.Print Space$((CurrentDepth + 1) * Indentation) & subFldr.Name
If CurrentDepth < MaxDepth Or MaxDepth = -1 Then
'Recursively call EnumerateFilesAndFolders
EnumerateFilesAndFolders subFldr.Path, MaxDepth, CurrentDepth + 1, Indentation
End If
Next subFldr
'Enumerate the files
Dim fil As Scripting.File
For Each fil In fldr.Files
Debug.Print Space$((CurrentDepth + 1) * Indentation) & fil.Name
Next fil
End If
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End Sub
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Chapter 35: Events
Section 35.1: Sources and Handlers
What are events?
VBA is event-driven: VBA code runs in response to events raised by the host application or the host document -
understanding events is fundamental to understanding VBA.
APIs often expose objects that raise a number of events in response to various states. For example an
Excel.Application object raises an event whenever a new workbook is created, opened, activated, or closed. Or
whenever a worksheet gets calculated. Or just before a file is saved. Or immediately after. A button on a form raises
a Click event when the user clicks it, the user form itself raises an event just after it's activated, and another just
before it's closed.
From an API perspective, events are extension points: the client code can chose to implement code that handles
these events, and execute custom code whenever these events are fired: that's how you can execute your custom
code automatically every time the selection changes on any worksheet - by handling the event that gets fired when
the selection changes on any worksheet.
An object that exposes events is an event source. A method that handles an event is a handler.
Handlers
VBA document modules (e.g. ThisDocument, ThisWorkbook, Sheet1, etc.) and UserForm modules are class modules
that implement special interfaces that expose a number of events. You can browse these interfaces in the left-side
dropdown at the top of the code pane:
The right-side dropdown lists the members of the interface selected in the left-side dropdown:
The VBE automatically generates an event handler stub when an item is selected on the right-side list, or navigates
there if the handler exists.
You can define a module-scoped WithEvents variable in any module:
GoalKicker.com – VBA Notes for Professionals 133
Private WithEvents Foo As Workbook
Private WithEvents Bar As Worksheet
Each WithEvents declaration becomes available to select from the left-side dropdown. When an event is selected in
the right-side dropdown, the VBE generates an event handler stub named after the WithEvents object and the
name of the event, joined with an underscore:
Private WithEvents Foo As Workbook
Private WithEvents Bar As Worksheet
Private Sub Foo_Open()
End Sub
Private Sub Bar_SelectionChange(ByVal Target As Range)
End Sub
Only types that expose at least one event can be used with WithEvents, and WithEvents declarations cannot be
assigned a reference on-the-spot with the New keyword. This code is illegal:
Private WithEvents Foo As New Workbook 'illegal
The object reference must be Set explicitly; in a class module, a good place to do that is often in the
Class_Initialize handler, because then the class handles that object's events for as long as its instance exists.
Sources
Any class module (or document module, or user form) can be an event source. Use the Event keyword to define the
signature for the event, in the declarations section of the module:
Public Event SomethingHappened(ByVal something As String)
The signature of the event determines how the event is raised, and what the event handlers will look like.
Events can only be raised within the class they're defined in - client code can only handle them. Events are raised
with the RaiseEvent keyword; the event's arguments are provided at that point:
Public Sub DoSomething()
RaiseEvent SomethingHappened("hello")
End Sub
Without code that handles the SomethingHappened event, running the DoSomething procedure will still raise the
event, but nothing will happen. Assuming the event source is the above code in a class named Something, this code
in ThisWorkbook would show a message box saying "hello" whenever test.DoSomething gets called:
Private WithEvents test As Something
Private Sub Workbook_Open()
Set test = New Something
test.DoSomething
End Sub
Private Sub test_SomethingHappened(ByVal bar As String)
'this procedure runs whenever 'test' raises the 'SomethingHappened' event
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MsgBox bar
End Sub
Section 35.2: Passing data back to the event source
Using parameters passed by reference
An event may define a ByRef parameter meant to be returned to the caller:
Public Event BeforeSomething(ByRef cancel As Boolean)
Public Event AfterSomething()
Public Sub DoSomething()
Dim cancel As Boolean
RaiseEvent BeforeSomething(cancel)
If cancel Then Exit Sub
'todo: actually do something
RaiseEvent AfterSomething
End Sub
If the BeforeSomething event has a handler that sets its cancel parameter to True, then when execution returns
from the handler, cancel will be True and AfterSomething will never be raised.
Private WithEvents foo As Something
Private Sub foo_BeforeSomething(ByRef cancel As Boolean)
cancel = MsgBox("Cancel?", vbYesNo) = vbYes
End Sub
Private Sub foo_AfterSomething()
MsgBox "Didn't cancel!"
End Sub
Assuming the foo object reference is assigned somewhere, when foo.DoSomething runs, a message box prompts
whether to cancel, and a second message box says "didn't cancel" only when No was selected.
Using mutable objects
You could also pass a copy of a mutable object ByVal, and let handlers modify that object's properties; the caller
can then read the modified property values and act accordingly.
'class module ReturnBoolean
Option Explicit
Private encapsulated As Boolean
Public Property Get ReturnValue() As Boolean
'Attribute ReturnValue.VB_UserMemId = 0
ReturnValue = encapsulated
End Property
Public Property Let ReturnValue(ByVal value As Boolean)
encapsulated = value
End Property
Combined with the Variant type, this can be used to create rather non-obvious ways to return a value to the caller:
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Public Event SomeEvent(ByVal foo As Variant)
Public Sub DoSomething()
Dim result As ReturnBoolean
result = New ReturnBoolean
RaiseEvent SomeEvent(result)
If result Then ' If result.ReturnValue Then
'handler changed the value to True
Else
'handler didn't modify the value
End If
End Sub
The handler would look like this:
Private Sub source_SomeEvent(ByVal foo As Variant) 'foo is actually a ReturnBoolean object
foo = True 'True is actually assigned to foo.ReturnValue, the class' default member
End Sub
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Chapter 36: Scripting.Dictionary object
You must add Microsoft Scripting Runtime to the VBA project through the VBE's Tools → References command in
order to implement early binding of the Scripting Dictionary object. This library reference is carried with the project;
it does not have to be re-referenced when the VBA project is distributed and run on another computer.
Section 36.1: Properties and Methods
A Scripting Dictionary object stores information in Key/Item pairs. The Keys must be unique and not an array but
the associated Items can be repeated (their uniqueness is held by the companion Key) and can be of any type of
variant or object.
A dictionary can be thought of as a two field in-memory database with a primary unique index on the first 'field'
(the Key). This unique index on the Keys property allows very fast 'lookups' to retrieve a Key's associated Item value.
Properties
name read/write type description
CompareMode read / write CompareMode
constant
Setting the CompareMode can only be performed on an empty
dictionary. Accepted values are 0 (vbBinaryCompare), 1
(vbTextCompare), 2 (vbDatabaseCompare).
Count read only unsigned long integer A one-based count of the key/item pairs in the scripting
dictionary object.
Key read / write non-array variant Each individual unique key in the dictionary.
Item(Key) read / write any variant
Default property. Each individual item associated with a key in
the dictionary. Note that attempting to retrieve an item with a
key that does not exist in the dictionary will implicitly add the
passed key.
Methods
name description
Add(Key,Item) Adds a new Key and Item to the dictionary. The new key must not exist in the dictionary's current
Keys collection but an item can be repeated among many unique keys.
Exists(Key) Boolean test to determine if a Key already exists in the dictionary.
Keys Returns the array or collection of unique keys.
Items Returns the array or collection of associated items.
Remove(Key) Removes an individual dictionary key and its associated item.
RemoveAll Clears all of a dictionary object's keys and items.
Sample Code
'Populate, enumerate, locate and remove entries in a dictionary that was created
'with late binding
Sub iterateDictionaryLate()
Dim k As Variant, dict As Object
Set dict = CreateObject("Scripting.Dictionary")
dict.CompareMode = vbTextCompare 'non-case sensitive compare model
'populate the dictionary
dict.Add Key:="Red", Item:="Balloon"
dict.Add Key:="Green", Item:="Balloon"
dict.Add Key:="Blue", Item:="Balloon"
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'iterate through the keys
For Each k In dict.Keys
Debug.Print k & " - " & dict.Item(k)
Next k
'locate the Item for Green
Debug.Print dict.Item("Green")
'remove key/item pairs from the dictionary
dict.Remove "blue" 'remove individual key/item pair by key
dict.RemoveAll 'remove all remaining key/item pairs
End Sub
'Populate, enumerate, locate and remove entries in a dictionary that was created
'with early binding (see Remarks)
Sub iterateDictionaryEarly()
Dim d As Long, k As Variant
Dim dict As New Scripting.Dictionary
dict.CompareMode = vbTextCompare 'non-case sensitive compare model
'populate the dictionary
dict.Add Key:="Red", Item:="Balloon"
dict.Add Key:="Green", Item:="Balloon"
dict.Add Key:="Blue", Item:="Balloon"
dict.Add Key:="White", Item:="Balloon"
'iterate through the keys
For Each k In dict.Keys
Debug.Print k & " - " & dict.Item(k)
Next k
'iterate through the keys by the count
For d = 0 To dict.Count - 1
Debug.Print dict.Keys(d) & " - " & dict.Items(d)
Next d
'iterate through the keys by the boundaries of the keys collection
For d = LBound(dict.Keys) To UBound(dict.Keys)
Debug.Print dict.Keys(d) & " - " & dict.Items(d)
Next d
'locate the Item for Green
Debug.Print dict.Item("Green")
'locate the Item for the first key
Debug.Print dict.Item(dict.Keys(0))
'locate the Item for the last key
Debug.Print dict.Item(dict.Keys(UBound(dict.Keys)))
'remove key/item pairs from the dictionary
dict.Remove "blue" 'remove individual key/item pair by key
dict.Remove dict.Keys(0) 'remove first key/item by index position
dict.Remove dict.Keys(UBound(dict.Keys)) 'remove last key/item by index position
dict.RemoveAll 'remove all remaining key/item pairs
End Sub
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Chapter 37: Working with ADO
Section 37.1: Making a connection to a data source
The first step in accessing a data source via ADO is creating an ADO Connection object. This is typically done using a
connection string to specify the data source parameters, although it is also possible to open a DSN connection by
passing the DSN, user ID, and password to the .Open method.
Note that a DSN is not required to connect to a data source via ADO - any data source that has an ODBC provider
can be connected to with the appropriate connection string. While specific connection strings for different
providers are outside of the scope of this topic, ConnectionStrings.com is an excellent reference for finding the
appropriate string for your provider.
Const SomeDSN As String = "DSN=SomeDSN;Uid=UserName;Pwd=MyPassword;"
Public Sub Example()
Dim database As ADODB.Connection
Set database = OpenDatabaseConnection(SomeDSN)
If Not database Is Nothing Then
'... Do work.
database.Close 'Make sure to close all database connections.
End If
End Sub
Public Function OpenDatabaseConnection(ConnString As String) As ADODB.Connection
On Error GoTo Handler
Dim database As ADODB.Connection
Set database = New ADODB.Connection
With database
.ConnectionString = ConnString
.ConnectionTimeout = 10 'Value is given in seconds.
.Open
End With
OpenDatabaseConnection = database
Exit Function
Handler:
Debug.Print "Database connection failed. Check your connection string."
End Function
Note that the database password is included in the connection string in the example above only for the sake of
clarity. Best practices would dictate not storing database passwords in code. This can be accomplished by taking
the password via user input or using Windows authentication.
Section 37.2: Creating parameterized commands
Any time SQL executed through an ADO connection needs to contain user input, it is considered best practice to
parameterize it in order to minimize the chance of SQL injection. This method is also more readable than long
concatenations and facilitates more robust and maintainable code (i.e. by using a function that returns an array of
Parameter).
In standard ODBC syntax, parameters are given ? "placeholders" in the query text, and then parameters are
appended to the Command in the same order that they appear in the query.
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Note that the example below uses the OpenDatabaseConnection function from the Making a connection to a data
source for brevity.
Public Sub UpdateTheFoos()
On Error GoTo Handler
Dim database As ADODB.Connection
Set database = OpenDatabaseConnection(SomeDSN)
If Not database Is Nothing Then
Dim update As ADODB.Command
Set update = New ADODB.Command
'Build the command to pass to the data source.
With update
.ActiveConnection = database
.CommandText = "UPDATE Table SET Foo = ? WHERE Bar = ?"
.CommandType = adCmdText
'Create the parameters.
Dim fooValue As ADODB.Parameter
Set fooValue = .CreateParameter("FooValue", adNumeric, adParamInput)
fooValue.Value = 42
Dim condition As ADODB.Parameter
Set condition = .CreateParameter("Condition", adBSTR, adParamInput)
condition.Value = "Bar"
'Add the parameters to the Command
.Parameters.Append fooValue
.Parameters.Append condition
.Execute
End With
End If
CleanExit:
If Not database Is Nothing And database.State = adStateOpen Then
database.Close
End If
Exit Sub
Handler:
Debug.Print "Error " & Err.Number & ": " & Err.Description
Resume CleanExit
End Sub
Note: The example above demonstrates a parameterized UPDATE statement, but any SQL statement can be given
parameters.
Section 37.3: Retrieving records with a query
Queries can be performed in two ways, both of which return an ADO Recordset object which is a collection of
returned rows. Note that both of the examples below use the OpenDatabaseConnection function from the Making a
connection to a data source example for the purpose of brevity. Remember that the syntax of the SQL passed to
the data source is provider specific.
The first method is to pass the SQL statement directly to the Connection object, and is the easiest method for
executing simple queries:
Public Sub DisplayDistinctItems()
On Error GoTo Handler
Dim database As ADODB.Connection
Set database = OpenDatabaseConnection(SomeDSN)
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If Not database Is Nothing Then
Dim records As ADODB.Recordset
Set records = database.Execute("SELECT DISTINCT Item FROM Table")
'Loop through the returned Recordset.
Do While Not records.EOF 'EOF is false when there are more records.
'Individual fields are indexed either by name or 0 based ordinal.
'Note that this is using the default .Fields member of the Recordset.
Debug.Print records("Item")
'Move to the next record.
records.MoveNext
Loop
End If
CleanExit:
If Not records Is Nothing Then records.Close
If Not database Is Nothing And database.State = adStateOpen Then
database.Close
End If
Exit Sub
Handler:
Debug.Print "Error " & Err.Number & ": " & Err.Description
Resume CleanExit
End Sub
The second method is to create an ADO Command object for the query you want to execute. This requires a little
more code, but is necessary in order to use parametrized queries:
Public Sub DisplayDistinctItems()
On Error GoTo Handler
Dim database As ADODB.Connection
Set database = OpenDatabaseConnection(SomeDSN)
If Not database Is Nothing Then
Dim query As ADODB.Command
Set query = New ADODB.Command
'Build the command to pass to the data source.
With query
.ActiveConnection = database
.CommandText = "SELECT DISTINCT Item FROM Table"
.CommandType = adCmdText
End With
Dim records As ADODB.Recordset
'Execute the command to retrieve the recordset.
Set records = query.Execute()
Do While Not records.EOF
Debug.Print records("Item")
records.MoveNext
Loop
End If
CleanExit:
If Not records Is Nothing Then records.Close
If Not database Is Nothing And database.State = adStateOpen Then
database.Close
End If
Exit Sub
Handler:
Debug.Print "Error " & Err.Number & ": " & Err.Description
Resume CleanExit
End Sub
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Note that commands sent to the data source are vulnerable to SQL injection, either intentional or unintentional.
In general, queries should not be created by concatenating user input of any kind. Instead, they should be
parameterized (see Creating parameterized commands).
Section 37.4: Executing non-scalar functions
ADO connections can be used to perform pretty much any database function that the provider supports via SQL. In
this case it isn't always necessary to use the Recordset returned by the Execute function, although it can be useful
for obtaining key assignments after INSERT statements with @@Identity or similar SQL commands. Note that the
example below uses the OpenDatabaseConnection function from the Making a connection to a data source example
for the purpose of brevity.
Public Sub UpdateTheFoos()
On Error GoTo Handler
Dim database As ADODB.Connection
Set database = OpenDatabaseConnection(SomeDSN)
If Not database Is Nothing Then
Dim update As ADODB.Command
Set update = New ADODB.Command
'Build the command to pass to the data source.
With update
.ActiveConnection = database
.CommandText = "UPDATE Table SET Foo = 42 WHERE Bar IS NULL"
.CommandType = adCmdText
.Execute 'We don't need the return from the DB, so ignore it.
End With
End If
CleanExit:
If Not database Is Nothing And database.State = adStateOpen Then
database.Close
End If
Exit Sub
Handler:
Debug.Print "Error " & Err.Number & ": " & Err.Description
Resume CleanExit
End Sub
Note that commands sent to the data source are vulnerable to SQL injection, either intentional or unintentional.
In general, SQL statements should not be created by concatenating user input of any kind. Instead, they should be
parameterized (see Creating parameterized commands).
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Chapter 38: Attributes
Section 38.1: VB_PredeclaredId
Creates a Global Default Instance of a class. The default instance is accessed via the name of the class.
Declaration
VERSION 1.0 CLASS
BEGIN
MultiUse = -1 'True
END
Attribute VB_Name = "Class1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Public Function GiveMeATwo() As Integer
GiveMeATwo = 2
End Function
Call
Debug.Print Class1.GiveMeATwo
In some ways, this simulates the behavior of static classes in other languages, but unlike other languages, you can
still create an instance of the class.
Dim cls As Class1
Set cls = New Class1
Debug.Print cls.GiveMeATwo
Section 38.2: VB_[Var]UserMemId
VB_VarUserMemId (for module-scope variables) and VB_UserMemId (for procedures) attributes are used in VBA
mostly for two things.
Specifying the default member of a class
A List class that would encapsulate a Collection would want to have an Item property, so the client code can do
this:
For i = 1 To myList.Count 'VBA Collection Objects are 1-based
Debug.Print myList.Item(i)
Next
But with a VB_UserMemId attribute set to 0 on the Item property, the client code can do this:
For i = 1 To myList.Count 'VBA Collection Objects are 1-based
Debug.Print myList(i)
Next
Only one member can legally have VB_UserMemId = 0 in any given class. For properties, specify the attribute in the
Get accessor:
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Option Explicit
Private internal As New Collection
Public Property Get Count() As Long
Count = internal.Count
End Property
Public Property Get Item(ByVal index As Long) As Variant
Attribute Item.VB_Description = "Gets or sets the element at the specified index."
Attribute Item.VB_UserMemId = 0
'Gets the element at the specified index.
Item = internal(index)
End Property
Public Property Let Item(ByVal index As Long, ByVal value As Variant)
'Sets the element at the specified index.
With internal
If index = .Count + 1 Then
.Add item:=value
ElseIf index = .Count Then
.Remove index
.Add item:=value
ElseIf index < .Count Then
.Remove index
.Add item:=value, before:=index
End If
End With
End Property
Making a class iteratable with a For Each loop construct
With the magic value -4, the VB_UserMemId attribute tells VBA that this member yields an enumerator - which allows
the client code to do this:
Dim item As Variant
For Each item In myList
Debug.Print item
Next
The easiest way to implement this method is by calling the hidden [_NewEnum] property getter on an
internal/encapsulated Collection; the identifier needs to be enclosed in square brackets because of the leading
underscore that makes it an illegal VBA identifier:
Public Property Get NewEnum() As IUnknown
Attribute NewEnum.VB_Description = "Gets an enumerator that iterates through the List."
Attribute NewEnum.VB_UserMemId = -4
Attribute NewEnum.VB_MemberFlags = "40" 'would hide the member in VB6. not supported in VBA.
'Gets an enumerator that iterates through the List.
Set NewEnum = internal.[_NewEnum]
End Property
Section 38.3: VB_Exposed
Controls the instancing characteristics of a class.
Attribute VB_Exposed = False
Makes the class Private. It cannot be accessed outside of the current project.
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Attribute VB_Exposed = True
Exposes the class Publicly, outside of the project. However, since VB_Createable is ignored in VBA, instances of the
class can not be created directly. This is equivalent to a the following VB.Net class.
Public Class Foo
Friend Sub New()
End Sub
End Class
In order to get an instance from outside the project, you must expose a factory to create instances. One way of
doing this is with a regular Public module.
Public Function CreateFoo() As Foo
CreateFoo = New Foo
End Function
Since public modules are accessible from other projects, this allows us to create new instances of our Public - Not
Createable classes.
Section 38.4: VB_Description
Adds a text description to a class or module member that becomes visible in the Object Explorer. Ideally, all public
members of a public interface / API should have a description.
Public Function GiveMeATwo() As Integer
Attribute GiveMeATwo.VB_Description = "Returns a two!"
GiveMeATwo = 2
End Property
Note: all accessor members of a property (Get, Let, Set) use the same description.
Section 38.5: VB_Name
VB_Name specifies the class or module name.
Attribute VB_Name = "Class1"
A new instance of this class would be created with
Dim myClass As Class1
myClass = new Class1
Section 38.6: VB_GlobalNameSpace
In VBA, this attribute is ignored. It was not ported over from VB6.
In VB6, it creates a Default Global Instance of the class (a "shortcut") so that class members can be accessed
without using the class name. For example, DateTime (as in DateTime.Now) is actually part of the VBA.Conversion
GoalKicker.com – VBA Notes for Professionals 145
class.
Debug.Print VBA.Conversion.DateTime.Now
Debug.Print DateTime.Now
Section 38.7: VB_Createable
This attribute is ignored. It was not ported over from VB6.
In VB6, it was used in combination with the VB_Exposed attribute to control accessibility of classes outside of the
current project.
VB_Exposed=True
VB_Creatable=True
Would result in a Public Class, that could be accessed from other projects, but this functionality does not exist in
VBA.
GoalKicker.com – VBA Notes for Professionals 146
Chapter 39: User Forms
Section 39.1: Best Practices
A UserForm is a class module with a designer and a default instance. The designer can be accessed by pressing
Shift + F7 while viewing the code-behind, and the code-behind can be accessed by pressing F7 while viewing
the designer.
Work with a new instance every time.
Being a class module, a form is therefore a blueprint for an object. Because a form can hold state and data, it's a
better practice to work with a new instance of the class, rather than with the default/global one:
With New UserForm1
.Show vbModal
If Not .IsCancelled Then
'...
End If
End With
Instead of:
UserForm1.Show vbModal
If Not UserForm1.IsCancelled Then
'...
End If
Working with the default instance can lead to subtle bugs when the form is closed with the red "X" button and/or
when Unload Me is used in the code-behind.
Implement the logic elsewhere.
A form should be concerned with nothing but presentation: a button Click handler that connects to a database and
runs a parameterized query based on user input, is doing too many things.
Instead, implement the applicative logic in the code that's responsible for displaying the form, or even better, in
dedicated modules and procedures.
Write the code in such a way that the UserForm is only ever responsible for knowing how to display and collect
data: where the data comes from, or what happens with the data afterwards, is none of its concern.
Caller shouldn't be bothered with controls.
Make a well-defined model for the form to work with, either in its own dedicated class module, or encapsulated
within the form's code-behind itself - expose the model with Property Get procedures, and have the client code
work with these: this makes the form an abstraction over controls and their nitty-gritty details, exposing only the
relevant data to the client code.
This means code that looks like this:
With New UserForm1
GoalKicker.com – VBA Notes for Professionals 147
.Show vbModal
If Not .IsCancelled Then
MsgBox .Message, vbInformation
End If
End With
Instead of this:
With New UserForm1
.Show vbModal
If Not .IsCancelled Then
MsgBox .txtMessage.Text, vbInformation
End If
End With
Handle the QueryClose event.
Forms typically have a Close button, and prompts/dialogs have Ok and Cancel buttons; the user may
close the form using the form's control box (the red "X" button), which destroys the form instance by default
(another good reason to work with a new instance every time).
With New UserForm1
.Show vbModal
If Not .IsCancelled Then 'if QueryClose isn't handled, this can raise a runtime error.
'...
End With
End With
The simplest way to handle the QueryClose event is to set the Cancel parameter to True, and then to hide the form
instead of closing it:
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
Cancel = True
Me.Hide
End Sub
That way the "X" button will never destroy the instance, and the caller can safely access all the public members.
Hide, don't close.
The code that creates an object should be responsible for destroying it: it's not the form's responsibility to unload
and terminate itself.
Avoid using Unload Me in a form's code-behind. Call Me.Hide instead, so that the calling code can still use the object
it created when the form closes.
Name things.
Use the properties toolwindow ( F4 ) to carefully name each control on a form. The name of a control is used in
the code-behind, so unless you're using a refactoring tool that can handle this, renaming a control will break the
code - so it's much easier to do things right in the first place, than try to puzzle out exactly which of the 20
textboxes TextBox12 stands for.
Traditionally, UserForm controls are named with Hungarian-style prefixes:
GoalKicker.com – VBA Notes for Professionals 148
lblUserName for a Label control that indicates a user name.
txtUserName for a TextBox control where the user can enter a user name.
cboUserName for a ComboBox control where the user can enter or pick a user name.
lstUserName for a ListBox control where the user can pick a user name.
btnOk or cmdOk for a Button control labelled "Ok".
The problem is that when e.g. the UI gets redesigned and a ComboBox changes to a ListBox, the name needs to
change to reflect the new control type: it's better to name controls for what they represent, rather than after their
control type - to decouple the code from the UI as much as possible.
UserNameLabel for a read-only label that indicates a user name.
UserNameInput for a control where the user can enter or pick a user name.
OkButton for a command button labelled "Ok".
Whichever style is chosen, anything is better than leaving all controls their default names. Consistency in naming
style is ideal, too.
Section 39.2: Handling QueryClose
The QueryClose event is raised whenever a form is about to be closed, whether it's via user action or
programmatically. The CloseMode parameter contains a VbQueryClose enum value that indicates how the form was
closed:
Constant Description Value
vbFormControlMenu Form is closing in response to user action 0
vbFormCode Form is closing in response to an Unload statement 1
vbAppWindows Windows session is ending 2
vbAppTaskManager Windows Task Manager is closing the host application 3
vbFormMDIForm Not supported in VBA 4
For better readability, it's best to use these constants instead of using their value directly.
A Cancellable UserForm
Given a form with a Cancel button
The form's code-behind could look like this:
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Option Explicit
Private Type TView
IsCancelled As Boolean
SomeOtherSetting As Boolean
'other properties skipped for brievety
End Type
Private this As TView
Public Property Get IsCancelled() As Boolean
IsCancelled = this.IsCancelled
End Property
Public Property Get SomeOtherSetting() As Boolean
SomeOtherSetting = this.SomeOtherSetting
End Property
'...more properties...
Private Sub SomeOtherSettingInput_Change()
this.SomeOtherSetting = CBool(SomeOtherSettingInput.Value)
End Sub
Private Sub OkButton_Click()
Me.Hide
End Sub
Private Sub CancelButton_Click()
this.IsCancelled = True
Me.Hide
End Sub
Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
If CloseMode = VbQueryClose.vbFormControlMenu Then
Cancel = True
this.IsCancelled = True
Me.Hide
End If
End Sub
The calling code could then display the form, and know whether it was cancelled:
Public Sub DoSomething()
With New UserForm1
.Show vbModal
If .IsCancelled Then Exit Sub
If .SomeOtherSetting Then
'setting is enabled
Else
'setting is disabled
End If
End With
End Sub
The IsCancelled property returns True when the Cancel button is clicked, or when the user closes the form
using the control box.
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Chapter 40: CreateObject vs. GetObject
Section 40.1: Demonstrating GetObject and CreateObject
MSDN-GetObject Function
Returns a reference to an object provided by an ActiveX component.
Use the GetObject function when there is a current instance of the object or if you want to create the
object with a file already loaded. If there is no current instance, and you don't want the object started
with a file loaded, use the CreateObject function.
Sub CreateVSGet()
Dim ThisXLApp As Excel.Application 'An example of early binding
Dim AnotherXLApp As Object 'An example of late binding
Dim ThisNewWB As Workbook
Dim AnotherNewWB As Workbook
Dim wb As Workbook
'Get this instance of Excel
Set ThisXLApp = GetObject(ThisWorkbook.Name).Application
'Create another instance of Excel
Set AnotherXLApp = CreateObject("Excel.Application")
'Make the 2nd instance visible
AnotherXLApp.Visible = True
'Add a workbook to the 2nd instance
Set AnotherNewWB = AnotherXLApp.Workbooks.Add
'Add a sheet to the 2nd instance
AnotherNewWB.Sheets.Add
'You should now have 2 instances of Excel open
'The 1st instance has 1 workbook: Book1
'The 2nd instance has 1 workbook: Book2
'Lets add another workbook to our 1st instance
Set ThisNewWB = ThisXLApp.Workbooks.Add
'Now loop through the workbooks and show their names
For Each wb In ThisXLApp.Workbooks
Debug.Print wb.Name
Next
'Now the 1st instance has 2 workbooks: Book1 and Book3
'If you close the first instance of Excel,
'Book1 and Book3 will close, but book2 will still be open
End Sub
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Chapter 41: Non-Latin Characters
VBA can read and write strings in any language or script using Unicode. However, there are stricter rules in place for
Identifier Tokens.
Section 41.1: Non-Latin Text in VBA Code
In spreadsheet cell A1, we have the following Arabic pangram:
صِف خَلقَ خَودِ كَمِثلِ الشَمسِ إِذ بَزَغَت — يَحظى الضَجيعُ بِها نَجلاءَ مِعطارِ
VBA provides the AscW and ChrW functions to work with multi-byte character codes. We can also use Byte arrays to
manipulate the string variable directly:
Sub NonLatinStrings()
Dim rng As Range
Set rng = Range("A1")
Do Until rng = ""
Dim MyString As String
MyString = rng.Value
' AscW functions
Dim char As String
char = AscW(Left(MyString, 1))
Debug.Print "First char (ChrW): " & char
Debug.Print "First char (binary): " & BinaryFormat(char, 12)
' ChrW functions
Dim uString As String
uString = ChrW(char)
Debug.Print "String value (text): " & uString ' Fails! Appears as '?'
Debug.Print "String value (AscW): " & AscW(uString)
' Using a Byte string
Dim StringAsByt() As Byte
StringAsByt = MyString
Dim i As Long
For i = 0 To 1 Step 2
Debug.Print "Byte values (in decimal): " & _
StringAsByt(i) & "|" & StringAsByt(i + 1)
Debug.Print "Byte values (binary): " & _
BinaryFormat(StringAsByt(i)) & "|" & BinaryFormat(StringAsByt(i + 1))
Next i
Debug.Print ""
' Printing the entire string to the immediate window fails (all '?'s)
Debug.Print "Whole String" & vbNewLine & rng.Value
Set rng = rng.Offset(1)
Loop
End Sub
This produces the following output for the Arabic Letter Sad:
First char (ChrW): 1589
First char (binary): 00011000110101
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String value (text): ?
String value (AscW): 1589
Byte values (in decimal): 53|6
Byte values (binary): 00110101|00000110
Whole String
??? ????? ????? ??????? ??????? ??? ??????? — ????? ???????? ???? ??????? ???????
Note that VBA is unable to print non-Latin text to the immediate window even though the string functions work
correctly. This is a limitation of the IDE and not the language.
Section 41.2: Non-Latin Identifiers and Language Coverage
VBA Identifiers (variable and function names) can use the Latin script and may also be able to use Japanese, Korean,
Simplified Chinese, and Traditional Chinese scripts.
The extended Latin script has full coverage for many languages:
English, French, Spanish, German, Italian, Breton, Catalan, Danish, Estonian, Finnish, Icelandic, Indonesian, Irish,
Lojban, Mapudungun, Norwegian, Portuguese, Scottish Gaelic, Swedish, Tagalog
Some languages are only partially covered:
Azeri, Croatian, Czech, Esperanto, Hungarian, Latvian, Lithuanian, Polish, Romanian, Serbian, Slovak, Slovenian,
Turkish, Yoruba, Welsh
Some languages have little or no coverage:
Arabic, Bulgarian, Cherokee, Dzongkha, Greek, Hindi, Macedonian, Malayalam, Mongolian, Russian, Sanskrit, Thai,
Tibetan, Urdu, Uyghur
The following variable declarations are all valid:
Dim Yec’hed As String 'Breton
Dim «Dóna» As String 'Catalan
Dim fræk As String 'Danish
Dim tšellomängija As String 'Estonian
Dim Törkylempijävongahdus As String 'Finnish
Dim j’examine As String 'French
Dim Paß As String 'German
Dim þjófum As String 'Icelandic
Dim hÓighe As String 'Irish
Dim sofybakni As String 'Lojban (.o’i does not work)
Dim ñizol As String 'Mapudungun
Dim Vår As String 'Norwegian
Dim «brações» As String 'Portuguese
Dim d’fhàg As String 'Scottish Gaelic
Note that in the VBA IDE, a single apostrophe within a variable name does not turn the line into a comment (as it
does on Stack Overflow).
Also, languages that use two angles to indicate a quote «» are allowed to use those in variable names desipte the
fact that the ""-type quotes are not.
GoalKicker.com – VBA Notes for Professionals 153
Chapter 42: API Calls
API stands for Application Programming Interface
API's for VBA imply a set of methods that allow direct interaction with the operating system
System calls can be made by executing procedures defined in DLL files
Section 42.1: Mac APIs
Microsoft doesn't officially support APIs but with some research more declarations can be found online
Office 2016 for Mac is sandboxed
Unlike other versions of Office apps that support VBA, Office 2016 for Mac apps are sandboxed.
Sandboxing restricts the apps from accessing resources outside the app container. This affects any add-ins or
macros that involve file access or communication across processes. You can minimize the effects of sandboxing by
using the new commands described in the following section. New VBA commands for Office 2016 for Mac
The following VBA commands are new and unique to Office 2016 for Mac.
Command Use to
GrantAccessToMultipleFiles Request a user's permission to access multiple files at once
AppleScriptTask Call external AppleScript scripts from VB
MAC_OFFICE_VERSION IFDEF between different Mac Office versions at compile time
Office 2011 for Mac
Private Declare Function system Lib "libc.dylib" (ByVal command As String) As Long
Private Declare Function popen Lib "libc.dylib" (ByVal command As String, ByVal mode As String) As
Long
Private Declare Function pclose Lib "libc.dylib" (ByVal file As Long) As Long
Private Declare Function fread Lib "libc.dylib" (ByVal outStr As String, ByVal size As Long, ByVal
items As Long, ByVal stream As Long) As Long
Private Declare Function feof Lib "libc.dylib" (ByVal file As Long) As Long
Office 2016 for Mac
Private Declare PtrSafe Function popen Lib "libc.dylib" (ByVal command As String, ByVal mode As
String) As LongPtr
Private Declare PtrSafe Function pclose Lib "libc.dylib" (ByVal file As LongPtr) As Long
Private Declare PtrSafe Function fread Lib "libc.dylib" (ByVal outStr As String, ByVal size As
LongPtr, ByVal items As LongPtr, ByVal stream As LongPtr) As Long
Private Declare PtrSafe Function feof Lib "libc.dylib" (ByVal file As LongPtr) As LongPtr
Section 42.2: Get total monitors and screen resolution
Option Explicit
'GetSystemMetrics32 info: http://msdn.microsoft.com/en-us/library/ms724385(VS.85).aspx
#If Win64 Then
Private Declare PtrSafe Function GetSystemMetrics32 Lib "User32" Alias "GetSystemMetrics"
(ByVal nIndex As Long) As Long
#ElseIf Win32 Then
GoalKicker.com – VBA Notes for Professionals 154
Private Declare Function GetSystemMetrics32 Lib "User32" Alias "GetSystemMetrics" (ByVal nIndex
As Long) As Long
#End If
'VBA Wrappers:
Public Function dllGetMonitors() As Long
Const SM_CMONITORS = 80
dllGetMonitors = GetSystemMetrics32(SM_CMONITORS)
End Function
Public Function dllGetHorizontalResolution() As Long
Const SM_CXVIRTUALSCREEN = 78
dllGetHorizontalResolution = GetSystemMetrics32(SM_CXVIRTUALSCREEN)
End Function
Public Function dllGetVerticalResolution() As Long
Const SM_CYVIRTUALSCREEN = 79
dllGetVerticalResolution = GetSystemMetrics32(SM_CYVIRTUALSCREEN)
End Function
Public Sub ShowDisplayInfo()
Debug.Print "Total monitors: " & vbTab & vbTab & dllGetMonitors
Debug.Print "Horizontal Resolution: " & vbTab & dllGetHorizontalResolution
Debug.Print "Vertical Resolution: " & vbTab & dllGetVerticalResolution
'Total monitors: 1
'Horizontal Resolution: 1920
'Vertical Resolution: 1080
End Sub
Section 42.3: FTP and Regional APIs
modFTP
Option Explicit
Option Compare Text
Option Private Module
'http://msdn.microsoft.com/en-us/library/aa384180(v=VS.85).aspx
'http://www.dailydoseofexcel.com/archives/2006/01/29/ftp-via-vba/
'http://www.15seconds.com/issue/981203.htm
'Open the Internet object
Private Declare Function InternetOpen Lib "wininet.dll" Alias "InternetOpenA" ( _
ByVal sAgent As String, _
ByVal lAccessType As Long, _
ByVal sProxyName As String, _
ByVal sProxyBypass As String, _
ByVal lFlags As Long _
) As Long
'ex: lngINet = InternetOpen(“MyFTP Control”, 1, vbNullString, vbNullString, 0)
'Connect to the network
Private Declare Function InternetConnect Lib "wininet.dll" Alias "InternetConnectA" ( _
ByVal hInternetSession As Long, _
ByVal sServerName As String, _
ByVal nServerPort As Integer, _
ByVal sUsername As String, _
ByVal sPassword As String, _
ByVal lService As Long, _
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ByVal lFlags As Long, _
ByVal lContext As Long _
) As Long
'ex: lngINetConn = InternetConnect(lngINet, "ftp.microsoft.com", 0, "anonymous",
"wally@wallyworld.com", 1, 0, 0)
'Get a file
Private Declare Function FtpGetFile Lib "wininet.dll" Alias "FtpGetFileA" ( _
ByVal hFtpSession As Long, _
ByVal lpszRemoteFile As String, _
ByVal lpszNewFile As String, _
ByVal fFailIfExists As Boolean, _
ByVal dwFlagsAndAttributes As Long, _
ByVal dwFlags As Long, _
ByVal dwContext As Long _
) As Boolean
'ex: blnRC = FtpGetFile(lngINetConn, "dirmap.txt", "c:\dirmap.txt", 0, 0, 1, 0)
'Send a file
Private Declare Function FtpPutFile Lib "wininet.dll" Alias "FtpPutFileA" _
( _
ByVal hFtpSession As Long, _
ByVal lpszLocalFile As String, _
ByVal lpszRemoteFile As String, _
ByVal dwFlags As Long, ByVal dwContext As Long _
) As Boolean
'ex: blnRC = FtpPutFile(lngINetConn, “c:\dirmap.txt”, “dirmap.txt”, 1, 0)
'Delete a file
Private Declare Function FtpDeleteFile Lib "wininet.dll" Alias "FtpDeleteFileA" _
( _
ByVal hFtpSession As Long, _
ByVal lpszFileName As String _
) As Boolean
'ex: blnRC = FtpDeleteFile(lngINetConn, “test.txt”)
'Close the Internet object
Private Declare Function InternetCloseHandle Lib "wininet.dll" (ByVal hInet As Long) As Integer
'ex: InternetCloseHandle lngINetConn
'ex: InternetCloseHandle lngINet
Private Declare Function FtpFindFirstFile Lib "wininet.dll" Alias "FtpFindFirstFileA" _
( _
ByVal hFtpSession As Long, _
ByVal lpszSearchFile As String, _
lpFindFileData As WIN32_FIND_DATA, _
ByVal dwFlags As Long, _
ByVal dwContent As Long _
) As Long
Private Type FILETIME
dwLowDateTime As Long
dwHighDateTime As Long
End Type
Private Type WIN32_FIND_DATA
dwFileAttributes As Long
ftCreationTime As FILETIME
ftLastAccessTime As FILETIME
ftLastWriteTime As FILETIME
nFileSizeHigh As Long
nFileSizeLow As Long
GoalKicker.com – VBA Notes for Professionals 156
dwReserved0 As Long
dwReserved1 As Long
cFileName As String * MAX_FTP_PATH
cAlternate As String * 14
End Type
'ex: lngHINet = FtpFindFirstFile(lngINetConn, "*.*", pData, 0, 0)
Private Declare Function InternetFindNextFile Lib "wininet.dll" Alias "InternetFindNextFileA" _
( _
ByVal hFind As Long, _
lpvFindData As WIN32_FIND_DATA _
) As Long
'ex: blnRC = InternetFindNextFile(lngHINet, pData)
Public Sub showLatestFTPVersion()
Dim ftpSuccess As Boolean, msg As String, lngFindFirst As Long
Dim lngINet As Long, lngINetConn As Long
Dim pData As WIN32_FIND_DATA
'init the filename buffer
pData.cFileName = String(260, 0)
msg = "FTP Error"
lngINet = InternetOpen("MyFTP Control", 1, vbNullString, vbNullString, 0)
If lngINet > 0 Then
lngINetConn = InternetConnect(lngINet, FTP_SERVER_NAME, FTP_SERVER_PORT, FTP_USER_NAME,
FTP_PASSWORD, 1, 0, 0)
If lngINetConn > 0 Then
FtpPutFile lngINetConn, "C:\Tmp\ftp.cls", "ftp.cls", FTP_TRANSFER_BINARY, 0
'lngFindFirst = FtpFindFirstFile(lngINetConn, "ExcelDiff.xlsm", pData, 0, 0)
If lngINet = 0 Then
msg = "DLL error: " & Err.LastDllError & ", Error Number: " & Err.Number & ", Error
Desc: " & Err.Description
Else
msg = left(pData.cFileName, InStr(1, pData.cFileName, String(1, 0),
vbBinaryCompare) - 1)
End If
InternetCloseHandle lngINetConn
End If
InternetCloseHandle lngINet
End If
MsgBox msg
End Sub
modRegional:
Option Explicit
Private Const LOCALE_SDECIMAL = &HE
Private Const LOCALE_SLIST = &HC
Private Declare Function GetLocaleInfo Lib "Kernel32" Alias "GetLocaleInfoA" (ByVal Locale As Long,
ByVal LCType As Long, ByVal lpLCData As String, ByVal cchData As Long) As Long
Private Declare Function SetLocaleInfo Lib "Kernel32" Alias "SetLocaleInfoA" (ByVal Locale As Long,
ByVal LCType As Long, ByVal lpLCData As String) As Boolean
Private Declare Function GetUserDefaultLCID% Lib "Kernel32" ()
Public Function getTimeSeparator() As String
getTimeSeparator = Application.International(xlTimeSeparator)
End Function
Public Function getDateSeparator() As String
GoalKicker.com – VBA Notes for Professionals 157
getDateSeparator = Application.International(xlDateSeparator)
End Function
Public Function getListSeparator() As String
Dim ListSeparator As String, iRetVal1 As Long, iRetVal2 As Long, lpLCDataVar As String,
Position As Integer, Locale As Long
Locale = GetUserDefaultLCID()
iRetVal1 = GetLocaleInfo(Locale, LOCALE_SLIST, lpLCDataVar, 0)
ListSeparator = String$(iRetVal1, 0)
iRetVal2 = GetLocaleInfo(Locale, LOCALE_SLIST, ListSeparator, iRetVal1)
Position = InStr(ListSeparator, Chr$(0))
If Position > 0 Then ListSeparator = Left$(ListSeparator, Position - 1) Else ListSeparator =
vbNullString
getListSeparator = ListSeparator
End Function
Private Sub ChangeSettingExample() 'change the setting of the character displayed as the decimal
separator.
Call SetLocalSetting(LOCALE_SDECIMAL, ",") 'to change to ","
Stop 'check your control panel to verify or use the
GetLocaleInfo API function
Call SetLocalSetting(LOCALE_SDECIMAL, ".") 'to back change to "."
End Sub
Private Function SetLocalSetting(LC_CONST As Long, Setting As String) As Boolean
Call SetLocaleInfo(GetUserDefaultLCID(), LC_CONST, Setting)
End Function
Section 42.4: API declaration and usage
Declaring a DLL procedure to work with different VBA versions:
Option Explicit
#If Win64 Then
Private Declare PtrSafe Sub xLib "Kernel32" Alias "Sleep" (ByVal dwMilliseconds As Long)
#ElseIf Win32 Then
Private Declare Sub apiSleep Lib "Kernel32" Alias "Sleep" (ByVal dwMilliseconds As Long)
#End If
The above declaration tells VBA how to call the function "Sleep" defined in file Kernel32.dll
Win64 and Win32 are predefined constants used for conditional compilation
Pre-defined Constants
Some compilation constants are already pre-defined. Which ones exist will depend on the bitness of the office
version you're running VBA in. Note that Vba7 was introduced alongside Office 2010 to support 64 bit versions of
Office.
Constant 16 bit 32 bit 64 bit
Vba6 False If Vba6 False
Vba7 False If Vba7 True
Win16 True False False
Win32 False True True
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Win64 False False True
Mac False If Mac If Mac
These constants refer to the Office version, not the Windows version. For example Win32 = TRUE in 32-bit Office,
even if the OS is a 64-bit version of Windows.
The main difference when declaring APIs is between 32 bit and 64 bit Office versions which introduced new
parameter types (see Remarks section for more details)
Notes:
Declarations are placed at the top of the module, and outside any Subs or Functions
Procedures declared in standard modules are public by default
To declare a procedure private to a module precede the declaration with the Private keyword
DLL procedures declared in any other type of module are private to that module
Simple example for the Sleep API call:
Public Sub TestPause()
Dim start As Double
start = Timer
Sleep 9000 'Pause execution for 9 seconds
Debug.Print "Paused for " & Format(Timer - start, "#,###.000") & " seconds"
'Immediate window result: Paused for 9.000 seconds
End Sub
It is recommended to create a dedicated API module to provide easy access to the system functions from VBA
wrappers -- normal VBA Subs or Functions that encapsulate the details needed for the actual system call such as
parameters used in libraries, and initialization of those parameters
The module can contain all declarations and dependencies:
Method signatures and required data structures
Wrappers that perform input validation, and ensure all parameters are passed as expected
To declare a DLL procedure, add a Declare statement to the Declarations section of the code window.
If the procedure returns a value, declare it as a Function:
Declare Function publicname Lib "libname" [Alias "alias"] [([[ByVal] variable [As type] [,[ByVal]
variable [As type]]...])] As Type
If a procedure does not return a value, declare it as a Sub:
Declare Sub publicname Lib "libname" [Alias "alias"] [([[ByVal] variable [As type] [,[ByVal]
variable [As type]]...])]
GoalKicker.com – VBA Notes for Professionals 159
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Also of note is that most invalid calls to the API's will crash Excel, and possibly corrupt data files
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Office 2011 for Mac
Private Declare Function system Lib "libc.dylib" (ByVal command As String) As Long
Sub RunSafari()
Dim result As Long
result = system("open -a Safari --args http://www.google.com")
Debug.Print Str(result)
End Sub
The examples bellow (Windows API - Dedicated Module (1 and 2)) show an API module that includes common
declarations for Win64 and Win32
Section 42.5: Windows API - Dedicated Module (1 of 2)
Option Explicit
#If Win64 Then 'Win64 = True, Win32 = False, Win16 = False
Private Declare PtrSafe Sub apiCopyMemory Lib "Kernel32" Alias "RtlMoveMemory" (MyDest As Any,
MySource As Any, ByVal MySize As Long)
Private Declare PtrSafe Sub apiExitProcess Lib "Kernel32" Alias "ExitProcess" (ByVal uExitCode
As Long)
Private Declare PtrSafe Sub apiSetCursorPos Lib "User32" Alias "SetCursorPos" (ByVal X As
Integer, ByVal Y As Integer)
Private Declare PtrSafe Sub apiSleep Lib "Kernel32" Alias "Sleep" (ByVal dwMilliseconds As
Long)
Private Declare PtrSafe Function apiAttachThreadInput Lib "User32" Alias "AttachThreadInput"
(ByVal idAttach As Long, ByVal idAttachTo As Long, ByVal fAttach As Long) As Long
Private Declare PtrSafe Function apiBringWindowToTop Lib "User32" Alias "BringWindowToTop"
(ByVal lngHWnd As Long) As Long
Private Declare PtrSafe Function apiCloseWindow Lib "User32" Alias "CloseWindow" (ByVal hWnd As
Long) As Long
Private Declare PtrSafe Function apiDestroyWindow Lib "User32" Alias "DestroyWindow" (ByVal
hWnd As Long) As Boolean
Private Declare PtrSafe Function apiEndDialog Lib "User32" Alias "EndDialog" (ByVal hWnd As
Long, ByVal result As Long) As Boolean
Private Declare PtrSafe Function apiEnumChildWindows Lib "User32" Alias "EnumChildWindows"
(ByVal hWndParent As Long, ByVal pEnumProc As Long, ByVal lParam As Long) As Long
Private Declare PtrSafe Function apiExitWindowsEx Lib "User32" Alias "ExitWindowsEx" (ByVal
uFlags As Long, ByVal dwReserved As Long) As Long
Private Declare PtrSafe Function apiFindExecutable Lib "Shell32" Alias "FindExecutableA" (ByVal
lpFile As String, ByVallpDirectory As String, ByVal lpResult As String) As Long
Private Declare PtrSafe Function apiFindWindow Lib "User32" Alias "FindWindowA" (ByVal
lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare PtrSafe Function apiFindWindowEx Lib "User32" Alias "FindWindowExA" (ByVal
hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare PtrSafe Function apiGetActiveWindow Lib "User32" Alias "GetActiveWindow" () As
Long
Private Declare PtrSafe Function apiGetClassNameA Lib "User32" Alias "GetClassNameA" (ByVal
hWnd As Long, ByVal szClassName As String, ByVal lLength As Long) As Long
Private Declare PtrSafe Function apiGetCommandLine Lib "Kernel32" Alias "GetCommandLineW" () As
Long
GoalKicker.com – VBA Notes for Professionals 160
Private Declare PtrSafe Function apiGetCommandLineParams Lib "Kernel32" Alias "GetCommandLineA"
() As Long
Private Declare PtrSafe Function apiGetDiskFreeSpaceEx Lib "Kernel32" Alias
"GetDiskFreeSpaceExA" (ByVal lpDirectoryName As String, lpFreeBytesAvailableToCaller As Currency,
lpTotalNumberOfBytes As Currency, lpTotalNumberOfFreeBytes As Currency) As Long
Private Declare PtrSafe Function apiGetDriveType Lib "Kernel32" Alias "GetDriveTypeA" (ByVal
nDrive As String) As Long
Private Declare PtrSafe Function apiGetExitCodeProcess Lib "Kernel32" Alias
"GetExitCodeProcess" (ByVal hProcess As Long, lpExitCode As Long) As Long
Private Declare PtrSafe Function apiGetForegroundWindow Lib "User32" Alias
"GetForegroundWindow" () As Long
Private Declare PtrSafe Function apiGetFrequency Lib "Kernel32" Alias
"QueryPerformanceFrequency" (cyFrequency As Currency) As Long
Private Declare PtrSafe Function apiGetLastError Lib "Kernel32" Alias "GetLastError" () As
Integer
Private Declare PtrSafe Function apiGetParent Lib "User32" Alias "GetParent" (ByVal hWnd As
Long) As Long
Private Declare PtrSafe Function apiGetSystemMetrics Lib "User32" Alias "GetSystemMetrics"
(ByVal nIndex As Long) As Long
Private Declare PtrSafe Function apiGetSystemMetrics32 Lib "User32" Alias "GetSystemMetrics"
(ByVal nIndex As Long) As Long
Private Declare PtrSafe Function apiGetTickCount Lib "Kernel32" Alias "QueryPerformanceCounter"
(cyTickCount As Currency) As Long
Private Declare PtrSafe Function apiGetTickCountMs Lib "Kernel32" Alias "GetTickCount" () As
Long
Private Declare PtrSafe Function apiGetUserName Lib "AdvApi32" Alias "GetUserNameA" (ByVal
lpBuffer As String, nSize As Long) As Long
Private Declare PtrSafe Function apiGetWindow Lib "User32" Alias "GetWindow" (ByVal hWnd As
Long, ByVal wCmd As Long) As Long
Private Declare PtrSafe Function apiGetWindowRect Lib "User32" Alias "GetWindowRect" (ByVal
hWnd As Long, lpRect As winRect) As Long
Private Declare PtrSafe Function apiGetWindowText Lib "User32" Alias "GetWindowTextA" (ByVal
hWnd As Long, ByVal szWindowText As String, ByVal lLength As Long) As Long
Private Declare PtrSafe Function apiGetWindowThreadProcessId Lib "User32" Alias
"GetWindowThreadProcessId" (ByVal hWnd As Long, lpdwProcessId As Long) As Long
Private Declare PtrSafe Function apiIsCharAlphaNumericA Lib "User32" Alias
"IsCharAlphaNumericA" (ByVal byChar As Byte) As Long
Private Declare PtrSafe Function apiIsIconic Lib "User32" Alias "IsIconic" (ByVal hWnd As Long)
As Long
Private Declare PtrSafe Function apiIsWindowVisible Lib "User32" Alias "IsWindowVisible" (ByVal
hWnd As Long) As Long
Private Declare PtrSafe Function apiIsZoomed Lib "User32" Alias "IsZoomed" (ByVal hWnd As Long)
As Long
Private Declare PtrSafe Function apiLStrCpynA Lib "Kernel32" Alias "lstrcpynA" (ByVal
pDestination As String, ByVal pSource As Long, ByVal iMaxLength As Integer) As Long
Private Declare PtrSafe Function apiMessageBox Lib "User32" Alias "MessageBoxA" (ByVal hWnd As
Long, ByVal lpText As String, ByVal lpCaption As String, ByVal wType As Long) As Long
Private Declare PtrSafe Function apiOpenIcon Lib "User32" Alias "OpenIcon" (ByVal hWnd As Long)
As Long
Private Declare PtrSafe Function apiOpenProcess Lib "Kernel32" Alias "OpenProcess" (ByVal
dwDesiredAccess As Long, ByVal bInheritHandle As Long, ByVal dwProcessId As Long) As Long
Private Declare PtrSafe Function apiPathAddBackslashByPointer Lib "ShlwApi" Alias
"PathAddBackslashW" (ByVal lpszPath As Long) As Long
Private Declare PtrSafe Function apiPathAddBackslashByString Lib "ShlwApi" Alias
"PathAddBackslashW" (ByVal lpszPath As String) As Long
'http://msdn.microsoft.com/en-us/library/aa155716%28office.10%29.aspx
Private Declare PtrSafe Function apiPostMessage Lib "User32" Alias "PostMessageA" (ByVal hWnd
As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare PtrSafe Function apiRegQueryValue Lib "AdvApi32" Alias "RegQueryValue" (ByVal
hKey As Long, ByVal sValueName As String, ByVal dwReserved As Long, ByRef lValueType As Long, ByVal
sValue As String, ByRef lResultLen As Long) As Long
Private Declare PtrSafe Function apiSendMessage Lib "User32" Alias "SendMessageA" (ByVal hWnd
GoalKicker.com – VBA Notes for Professionals 161
As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare PtrSafe Function apiSetActiveWindow Lib "User32" Alias "SetActiveWindow" (ByVal
hWnd As Long) As Long
Private Declare PtrSafe Function apiSetCurrentDirectoryA Lib "Kernel32" Alias
"SetCurrentDirectoryA" (ByVal lpPathName As String) As Long
Private Declare PtrSafe Function apiSetFocus Lib "User32" Alias "SetFocus" (ByVal hWnd As Long)
As Long
Private Declare PtrSafe Function apiSetForegroundWindow Lib "User32" Alias
"SetForegroundWindow" (ByVal hWnd As Long) As Long
Private Declare PtrSafe Function apiSetLocalTime Lib "Kernel32" Alias "SetLocalTime" (lpSystem
As SystemTime) As Long
Private Declare PtrSafe Function apiSetWindowPlacement Lib "User32" Alias "SetWindowPlacement"
(ByVal hWnd As Long, ByRef lpwndpl As winPlacement) As Long
Private Declare PtrSafe Function apiSetWindowPos Lib "User32" Alias "SetWindowPos" (ByVal hWnd
As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal
cy As Long, ByVal wFlags As Long) As Long
Private Declare PtrSafe Function apiSetWindowText Lib "User32" Alias "SetWindowTextA" (ByVal
hWnd As Long, ByVal lpString As String) As Long
Private Declare PtrSafe Function apiShellExecute Lib "Shell32" Alias "ShellExecuteA" (ByVal
hWnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String,
ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long
Private Declare PtrSafe Function apiShowWindow Lib "User32" Alias "ShowWindow" (ByVal hWnd As
Long, ByVal nCmdShow As Long) As Long
Private Declare PtrSafe Function apiShowWindowAsync Lib "User32" Alias "ShowWindowAsync" (ByVal
hWnd As Long, ByVal nCmdShow As Long) As Long
Private Declare PtrSafe Function apiStrCpy Lib "Kernel32" Alias "lstrcpynA" (ByVal pDestination
As String, ByVal pSource As String, ByVal iMaxLength As Integer) As Long
Private Declare PtrSafe Function apiStringLen Lib "Kernel32" Alias "lstrlenW" (ByVal lpString
As Long) As Long
Private Declare PtrSafe Function apiStrTrimW Lib "ShlwApi" Alias "StrTrimW" () As Boolean
Private Declare PtrSafe Function apiTerminateProcess Lib "Kernel32" Alias "TerminateProcess"
(ByVal hWnd As Long, ByVal uExitCode As Long) As Long
Private Declare PtrSafe Function apiTimeGetTime Lib "Winmm" Alias "timeGetTime" () As Long
Private Declare PtrSafe Function apiVarPtrArray Lib "MsVbVm50" Alias "VarPtr" (Var() As Any) As
Long
Private Type browseInfo 'used by apiBrowseForFolder
hOwner As Long
pidlRoot As Long
pszDisplayName As String
lpszTitle As String
ulFlags As Long
lpfn As Long
lParam As Long
iImage As Long
End Type
Private Declare PtrSafe Function apiBrowseForFolder Lib "Shell32" Alias "SHBrowseForFolderA"
(lpBrowseInfo As browseInfo) As Long
Private Type CHOOSECOLOR 'used by apiChooseColor; http://support.microsoft.com/kb/153929 and
http://www.cpearson.com/Excel/Colors.aspx
lStructSize As Long
hWndOwner As Long
hInstance As Long
rgbResult As Long
lpCustColors As String
flags As Long
lCustData As Long
lpfnHook As Long
lpTemplateName As String
End Type
Private Declare PtrSafe Function apiChooseColor Lib "ComDlg32" Alias "ChooseColorA"
(pChoosecolor As CHOOSECOLOR) As Long
Private Type FindWindowParameters 'Custom structure for passing in the parameters in/out of
GoalKicker.com – VBA Notes for Professionals 162
the hook enumeration function; could use global variables instead, but this is nicer
strTitle As String 'INPUT
hWnd As Long 'OUTPUT
End Type 'Find a specific window with dynamic caption from a list of
all open windows:
http://www.everythingaccess.com/tutorials.asp?ID=Bring-an-external-application-window-to-the-foregrou
nd
Private Declare PtrSafe Function apiEnumWindows Lib "User32" Alias "EnumWindows" (ByVal
lpEnumFunc As LongPtr, ByVal lParam As LongPtr) As Long
Private Type lastInputInfo 'used by apiGetLastInputInfo, getLastInputTime
cbSize As Long
dwTime As Long
End Type
Private Declare PtrSafe Function apiGetLastInputInfo Lib "User32" Alias "GetLastInputInfo"
(ByRef plii As lastInputInfo) As Long
'http://www.pgacon.com/visualbasic.htm#Take%20Advantage%20of%20Conditional%20Compilation
'Logical and Bitwise Operators in Visual Basic:
http://msdn.microsoft.com/en-us/library/wz3k228a(v=vs.80).aspx and
http://stackoverflow.com/questions/1070863/hidden-features-of-vba
Private Type SystemTime
wYear As Integer
wMonth As Integer
wDayOfWeek As Integer
wDay As Integer
wHour As Integer
wMinute As Integer
wSecond As Integer
wMilliseconds As Integer
End Type
Private Declare PtrSafe Sub apiGetLocalTime Lib "Kernel32" Alias "GetLocalTime" (lpSystem As
SystemTime)
Private Type pointAPI 'used by apiSetWindowPlacement
X As Long
Y As Long
End Type
Private Type rectAPI 'used by apiSetWindowPlacement
Left_Renamed As Long
Top_Renamed As Long
Right_Renamed As Long
Bottom_Renamed As Long
End Type
Private Type winPlacement 'used by apiSetWindowPlacement
length As Long
flags As Long
showCmd As Long
ptMinPosition As pointAPI
ptMaxPosition As pointAPI
rcNormalPosition As rectAPI
End Type
Private Declare PtrSafe Function apiGetWindowPlacement Lib "User32" Alias "GetWindowPlacement"
(ByVal hWnd As Long, ByRef lpwndpl As winPlacement) As Long
Private Type winRect 'used by apiMoveWindow
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
Private Declare PtrSafe Function apiMoveWindow Lib "User32" Alias "MoveWindow" (ByVal hWnd As
Long, xLeft As Long, ByVal yTop As Long, wWidth As Long, ByVal hHeight As Long, ByVal repaint As
Long) As Long
Private Declare PtrSafe Function apiInternetOpen Lib "WiniNet" Alias "InternetOpenA" (ByVal
GoalKicker.com – VBA Notes for Professionals 163
sAgent As String, ByVal lAccessType As Long, ByVal sProxyName As String, ByVal sProxyBypass As
String, ByVal lFlags As Long) As Long 'Open the Internet object 'ex: lngINet =
InternetOpen(“MyFTP Control”, 1, vbNullString, vbNullString, 0)
Private Declare PtrSafe Function apiInternetConnect Lib "WiniNet" Alias "InternetConnectA"
(ByVal hInternetSession As Long, ByVal sServerName As String, ByVal nServerPort As Integer, ByVal
sUsername As String, ByVal sPassword As String, ByVal lService As Long, ByVal lFlags As Long, ByVal
lContext As Long) As Long 'Connect to the network 'ex: lngINetConn = InternetConnect(lngINet,
"ftp.microsoft.com", 0, "anonymous", "wally@wallyworld.com", 1, 0, 0)
Private Declare PtrSafe Function apiFtpGetFile Lib "WiniNet" Alias "FtpGetFileA" (ByVal
hFtpSession As Long, ByVal lpszRemoteFile As String, ByVal lpszNewFile As String, ByVal
fFailIfExists As Boolean, ByVal dwFlagsAndAttributes As Long, ByVal dwFlags As Long, ByVal
dwContext As Long) As Boolean 'Get a file 'ex: blnRC = FtpGetFile(lngINetConn, "dirmap.txt",
"c:\dirmap.txt", 0, 0, 1, 0)
Private Declare PtrSafe Function apiFtpPutFile Lib "WiniNet" Alias "FtpPutFileA" (ByVal
hFtpSession As Long, ByVal lpszLocalFile As String, ByVal lpszRemoteFile As String, ByVal dwFlags
As Long, ByVal dwContext As Long) As Boolean 'Send a file 'ex: blnRC = FtpPutFile(lngINetConn,
“c:\dirmap.txt”, “dirmap.txt”, 1, 0)
Private Declare PtrSafe Function apiFtpDeleteFile Lib "WiniNet" Alias "FtpDeleteFileA" (ByVal
hFtpSession As Long, ByVal lpszFileName As String) As Boolean 'Delete a file 'ex: blnRC =
FtpDeleteFile(lngINetConn, “test.txt”)
Private Declare PtrSafe Function apiInternetCloseHandle Lib "WiniNet" (ByVal hInet As Long) As
Integer 'Close the Internet object 'ex: InternetCloseHandle lngINetConn 'ex: InternetCloseHandle
lngINet
Private Declare PtrSafe Function apiFtpFindFirstFile Lib "WiniNet" Alias "FtpFindFirstFileA"
(ByVal hFtpSession As Long, ByVal lpszSearchFile As String, lpFindFileData As WIN32_FIND_DATA,
ByVal dwFlags As Long, ByVal dwContent As Long) As Long
Private Type FILETIME
dwLowDateTime As Long
dwHighDateTime As Long
End Type
Private Type WIN32_FIND_DATA
dwFileAttributes As Long
ftCreationTime As FILETIME
ftLastAccessTime As FILETIME
ftLastWriteTime As FILETIME
nFileSizeHigh As Long
nFileSizeLow As Long
dwReserved0 As Long
dwReserved1 As Long
cFileName As String * 1 'MAX_FTP_PATH
cAlternate As String * 14
End Type 'ex: lngHINet = FtpFindFirstFile(lngINetConn, "*.*", pData, 0, 0)
Private Declare PtrSafe Function apiInternetFindNextFile Lib "WiniNet" Alias
"InternetFindNextFileA" (ByVal hFind As Long, lpvFindData As WIN32_FIND_DATA) As Long 'ex: blnRC =
InternetFindNextFile(lngHINet, pData)
#ElseIf Win32 Then 'Win32 = True, Win16 = False
(continued in second example)
Section 42.6: Windows API - Dedicated Module (2 of 2)
#ElseIf Win32 Then 'Win32 = True, Win16 = False
Private Declare Sub apiCopyMemory Lib "Kernel32" Alias "RtlMoveMemory" (MyDest As Any, MySource
As Any, ByVal MySize As Long)
Private Declare Sub apiExitProcess Lib "Kernel32" Alias "ExitProcess" (ByVal uExitCode As Long)
'Private Declare Sub apiGetStartupInfo Lib "Kernel32" Alias "GetStartupInfoA" (lpStartupInfo As
STARTUPINFO)
Private Declare Sub apiSetCursorPos Lib "User32" Alias "SetCursorPos" (ByVal X As Integer,
ByVal Y As Integer) 'Logical and Bitwise Operators in Visual Basic:
http://msdn.microsoft.com/en-us/library/wz3k228a(v=vs.80).aspx and
http://stackoverflow.com/questions/1070863/hidden-features-of-vba
GoalKicker.com – VBA Notes for Professionals 164
'http://www.pgacon.com/visualbasic.htm#Take%20Advantage%20of%20Conditional%20Compilation
Private Declare Sub apiSleep Lib "Kernel32" Alias "Sleep" (ByVal dwMilliseconds As Long)
Private Declare Function apiAttachThreadInput Lib "User32" Alias "AttachThreadInput" (ByVal
idAttach As Long, ByVal idAttachTo As Long, ByVal fAttach As Long) As Long
Private Declare Function apiBringWindowToTop Lib "User32" Alias "BringWindowToTop" (ByVal
lngHWnd As Long) As Long
Private Declare Function apiCloseHandle Lib "Kernel32" (ByVal hObject As Long) As Long
Private Declare Function apiCloseWindow Lib "User32" Alias "CloseWindow" (ByVal hWnd As Long)
As Long
'Private Declare Function apiCreatePipe Lib "Kernel32" (phReadPipe As Long, phWritePipe As Long,
lpPipeAttributes As SECURITY_ATTRIBUTES, ByVal nSize As Long) As Long
'Private Declare Function apiCreateProcess Lib "Kernel32" Alias "CreateProcessA" (ByVal
lpApplicationName As Long, ByVal lpCommandLine As String, lpProcessAttributes As Any,
lpThreadAttributes As Any, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long,
lpEnvironment As Any, ByVal lpCurrentDriectory As String, lpStartupInfo As STARTUPINFO,
lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Function apiDestroyWindow Lib "User32" Alias "DestroyWindow" (ByVal hWnd As
Long) As Boolean
Private Declare Function apiEndDialog Lib "User32" Alias "EndDialog" (ByVal hWnd As Long, ByVal
result As Long) As Boolean
Private Declare Function apiEnumChildWindows Lib "User32" Alias "EnumChildWindows" (ByVal
hWndParent As Long, ByVal pEnumProc As Long, ByVal lParam As Long) As Long
Private Declare Function apiExitWindowsEx Lib "User32" Alias "ExitWindowsEx" (ByVal uFlags As
Long, ByVal dwReserved As Long) As Long
Private Declare Function apiFindExecutable Lib "Shell32" Alias "FindExecutableA" (ByVal lpFile
As String, ByVallpDirectory As String, ByVal lpResult As String) As Long
Private Declare Function apiFindWindow Lib "User32" Alias "FindWindowA" (ByVal lpClassName As
String, ByVal lpWindowName As String) As Long
Private Declare Function apiFindWindowEx Lib "User32" Alias "FindWindowExA" (ByVal hWnd1 As
Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare Function apiGetActiveWindow Lib "User32" Alias "GetActiveWindow" () As Long
Private Declare Function apiGetClassNameA Lib "User32" Alias "GetClassNameA" (ByVal hWnd As
Long, ByVal szClassName As String, ByVal lLength As Long) As Long
Private Declare Function apiGetCommandLine Lib "Kernel32" Alias "GetCommandLineW" () As Long
Private Declare Function apiGetCommandLineParams Lib "Kernel32" Alias "GetCommandLineA" () As
Long
Private Declare Function apiGetDiskFreeSpaceEx Lib "Kernel32" Alias "GetDiskFreeSpaceExA"
(ByVal lpDirectoryName As String, lpFreeBytesAvailableToCaller As Currency, lpTotalNumberOfBytes As
Currency, lpTotalNumberOfFreeBytes As Currency) As Long
Private Declare Function apiGetDriveType Lib "Kernel32" Alias "GetDriveTypeA" (ByVal nDrive As
String) As Long
Private Declare Function apiGetExitCodeProcess Lib "Kernel32" (ByVal hProcess As Long,
lpExitCode As Long) As Long
Private Declare Function apiGetFileSize Lib "Kernel32" (ByVal hFile As Long, lpFileSizeHigh As
Long) As Long
Private Declare Function apiGetForegroundWindow Lib "User32" Alias "GetForegroundWindow" () As
Long
Private Declare Function apiGetFrequency Lib "Kernel32" Alias "QueryPerformanceFrequency"
(cyFrequency As Currency) As Long
Private Declare Function apiGetLastError Lib "Kernel32" Alias "GetLastError" () As Integer
Private Declare Function apiGetParent Lib "User32" Alias "GetParent" (ByVal hWnd As Long) As
Long
Private Declare Function apiGetSystemMetrics Lib "User32" Alias "GetSystemMetrics" (ByVal
nIndex As Long) As Long
Private Declare Function apiGetTickCount Lib "Kernel32" Alias "QueryPerformanceCounter"
(cyTickCount As Currency) As Long
Private Declare Function apiGetTickCountMs Lib "Kernel32" Alias "GetTickCount" () As Long
Private Declare Function apiGetUserName Lib "AdvApi32" Alias "GetUserNameA" (ByVal lpBuffer As
String, nSize As Long) As Long
Private Declare Function apiGetWindow Lib "User32" Alias "GetWindow" (ByVal hWnd As Long, ByVal
wCmd As Long) As Long
Private Declare Function apiGetWindowRect Lib "User32" Alias "GetWindowRect" (ByVal hWnd As
GoalKicker.com – VBA Notes for Professionals 165
Long, lpRect As winRect) As Long
Private Declare Function apiGetWindowText Lib "User32" Alias "GetWindowTextA" (ByVal hWnd As
Long, ByVal szWindowText As String, ByVal lLength As Long) As Long
Private Declare Function apiGetWindowThreadProcessId Lib "User32" Alias
"GetWindowThreadProcessId" (ByVal hWnd As Long, lpdwProcessId As Long) As Long
Private Declare Function apiIsCharAlphaNumericA Lib "User32" Alias "IsCharAlphaNumericA" (ByVal
byChar As Byte) As Long
Private Declare Function apiIsIconic Lib "User32" Alias "IsIconic" (ByVal hWnd As Long) As Long
Private Declare Function apiIsWindowVisible Lib "User32" Alias "IsWindowVisible" (ByVal hWnd As
Long) As Long
Private Declare Function apiIsZoomed Lib "User32" Alias "IsZoomed" (ByVal hWnd As Long) As Long
Private Declare Function apiLStrCpynA Lib "Kernel32" Alias "lstrcpynA" (ByVal pDestination As
String, ByVal pSource As Long, ByVal iMaxLength As Integer) As Long
Private Declare Function apiMessageBox Lib "User32" Alias "MessageBoxA" (ByVal hWnd As Long,
ByVal lpText As String, ByVal lpCaption As String, ByVal wType As Long) As Long
Private Declare Function apiOpenIcon Lib "User32" Alias "OpenIcon" (ByVal hWnd As Long) As Long
Private Declare Function apiOpenProcess Lib "Kernel32" Alias "OpenProcess" (ByVal
dwDesiredAccess As Long, ByVal bInheritHandle As Long, ByVal dwProcessId As Long) As Long
Private Declare Function apiPathAddBackslashByPointer Lib "ShlwApi" Alias "PathAddBackslashW"
(ByVal lpszPath As Long) As Long
Private Declare Function apiPathAddBackslashByString Lib "ShlwApi" Alias "PathAddBackslashW"
(ByVal lpszPath As String) As Long
'http://msdn.microsoft.com/en-us/library/aa155716%28office.10%29.aspx
Private Declare Function apiPostMessage Lib "User32" Alias "PostMessageA" (ByVal hWnd As Long,
ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function apiReadFile Lib "Kernel32" (ByVal hFile As Long, lpBuffer As Any,
ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, lpOverlapped As Any) As Long
Private Declare Function apiRegQueryValue Lib "AdvApi32" Alias "RegQueryValue" (ByVal hKey As
Long, ByVal sValueName As String, ByVal dwReserved As Long, ByRef lValueType As Long, ByVal sValue
As String, ByRef lResultLen As Long) As Long
Private Declare Function apiSendMessage Lib "User32" Alias "SendMessageA" (ByVal hWnd As Long,
ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function apiSetActiveWindow Lib "User32" Alias "SetActiveWindow" (ByVal hWnd As
Long) As Long
Private Declare Function apiSetCurrentDirectoryA Lib "Kernel32" Alias "SetCurrentDirectoryA"
(ByVal lpPathName As String) As Long
Private Declare Function apiSetFocus Lib "User32" Alias "SetFocus" (ByVal hWnd As Long) As Long
Private Declare Function apiSetForegroundWindow Lib "User32" Alias "SetForegroundWindow" (ByVal
hWnd As Long) As Long
Private Declare Function apiSetLocalTime Lib "Kernel32" Alias "SetLocalTime" (lpSystem As
SystemTime) As Long
Private Declare Function apiSetWindowPlacement Lib "User32" Alias "SetWindowPlacement" (ByVal
hWnd As Long, ByRef lpwndpl As winPlacement) As Long
Private Declare Function apiSetWindowPos Lib "User32" Alias "SetWindowPos" (ByVal hWnd As Long,
ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As
Long, ByVal wFlags As Long) As Long
Private Declare Function apiSetWindowText Lib "User32" Alias "SetWindowTextA" (ByVal hWnd As
Long, ByVal lpString As String) As Long
Private Declare Function apiShellExecute Lib "Shell32" Alias "ShellExecuteA" (ByVal hWnd As
Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal
lpDirectory As String, ByVal nShowCmd As Long) As Long
Private Declare Function apiShowWindow Lib "User32" Alias "ShowWindow" (ByVal hWnd As Long,
ByVal nCmdShow As Long) As Long
Private Declare Function apiShowWindowAsync Lib "User32" Alias "ShowWindowAsync" (ByVal hWnd As
Long, ByVal nCmdShow As Long) As Long
Private Declare Function apiStrCpy Lib "Kernel32" Alias "lstrcpynA" (ByVal pDestination As
String, ByVal pSource As String, ByVal iMaxLength As Integer) As Long
Private Declare Function apiStringLen Lib "Kernel32" Alias "lstrlenW" (ByVal lpString As Long)
As Long
Private Declare Function apiStrTrimW Lib "ShlwApi" Alias "StrTrimW" () As Boolean
Private Declare Function apiTerminateProcess Lib "Kernel32" Alias "TerminateProcess" (ByVal
hWnd As Long, ByVal uExitCode As Long) As Long
GoalKicker.com – VBA Notes for Professionals 166
Private Declare Function apiTimeGetTime Lib "Winmm" Alias "timeGetTime" () As Long
Private Declare Function apiVarPtrArray Lib "MsVbVm50" Alias "VarPtr" (Var() As Any) As Long
Private Declare Function apiWaitForSingleObject Lib "Kernel32" (ByVal hHandle As Long, ByVal
dwMilliseconds As Long) As Long
Private Type browseInfo 'used by apiBrowseForFolder
hOwner As Long
pidlRoot As Long
pszDisplayName As String
lpszTitle As String
ulFlags As Long
lpfn As Long
lParam As Long
iImage As Long
End Type
Private Declare Function apiBrowseForFolder Lib "Shell32" Alias "SHBrowseForFolderA"
(lpBrowseInfo As browseInfo) As Long
Private Type CHOOSECOLOR 'used by apiChooseColor; http://support.microsoft.com/kb/153929 and
http://www.cpearson.com/Excel/Colors.aspx
lStructSize As Long
hWndOwner As Long
hInstance As Long
rgbResult As Long
lpCustColors As String
flags As Long
lCustData As Long
lpfnHook As Long
lpTemplateName As String
End Type
Private Declare Function apiChooseColor Lib "ComDlg32" Alias "ChooseColorA" (pChoosecolor As
CHOOSECOLOR) As Long
Private Type FindWindowParameters 'Custom structure for passing in the parameters in/out of
the hook enumeration function; could use global variables instead, but this is nicer
strTitle As String 'INPUT
hWnd As Long 'OUTPUT
End Type 'Find a specific window with dynamic caption from a list of
all open windows:
http://www.everythingaccess.com/tutorials.asp?ID=Bring-an-external-application-window-to-the-foregrou
nd
Private Declare Function apiEnumWindows Lib "User32" Alias "EnumWindows" (ByVal lpEnumFunc As
Long, ByVal lParam As Long) As Long
Private Type lastInputInfo 'used by apiGetLastInputInfo, getLastInputTime
cbSize As Long
dwTime As Long
End Type
Private Declare Function apiGetLastInputInfo Lib "User32" Alias "GetLastInputInfo" (ByRef plii
As lastInputInfo) As Long
Private Type SystemTime
wYear As Integer
wMonth As Integer
wDayOfWeek As Integer
wDay As Integer
wHour As Integer
wMinute As Integer
wSecond As Integer
wMilliseconds As Integer
End Type
Private Declare Sub apiGetLocalTime Lib "Kernel32" Alias "GetLocalTime" (lpSystem As
SystemTime)
Private Type pointAPI
X As Long
Y As Long
End Type
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Private Type rectAPI
Left_Renamed As Long
Top_Renamed As Long
Right_Renamed As Long
Bottom_Renamed As Long
End Type
Private Type winPlacement
length As Long
flags As Long
showCmd As Long
ptMinPosition As pointAPI
ptMaxPosition As pointAPI
rcNormalPosition As rectAPI
End Type
Private Declare Function apiGetWindowPlacement Lib "User32" Alias "GetWindowPlacement" (ByVal
hWnd As Long, ByRef lpwndpl As winPlacement) As Long
Private Type winRect
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type
Private Declare Function apiMoveWindow Lib "User32" Alias "MoveWindow" (ByVal hWnd As Long,
xLeft As Long, ByVal yTop As Long, wWidth As Long, ByVal hHeight As Long, ByVal repaint As Long) As
Long
#Else ' Win16 = True
#End If
GoalKicker.com – VBA Notes for Professionals 168
Chapter 43: Automation or Using other
applications Libraries
If you use the objects in other applications as part of your Visual Basic application, you may want to establish a
reference to the object libraries of those applications. This Documentation provides a list, sources and examples of
how to use libraries of different softwares, like Windows Shell, Internet Explorer, XML HttpRequest, and others.
Section 43.1: VBScript Regular Expressions
Set createVBScriptRegExObject = CreateObject("vbscript.RegExp")
Tools> References> Microsoft VBScript Regular Expressions #.#
Associated DLL: VBScript.dll
Source: Internet Explorer 1.0 and 5.5
MSDN-Microsoft Beefs Up VBScript with Regular Expressions
MSDN-Regular Expression Syntax (Scripting)
experts-exchange - Using Regular Expressions in Visual Basic for Applications and Visual Basic 6
How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops on SO.
regular-expressions.info/vbscript
regular-expressions.info/vbscriptexample
WIKI-Regular expression
Code
You can use this functions to get RegEx results, concatenate all matches (if more than 1) into 1 string, and display
result in excel cell.
Public Function getRegExResult(ByVal SourceString As String, Optional ByVal RegExPattern As String
= "\d+", _
Optional ByVal isGlobalSearch As Boolean = True, Optional ByVal isCaseSensitive As Boolean =
False, Optional ByVal Delimiter As String = ";") As String
Static RegExObject As Object
If RegExObject Is Nothing Then
Set RegExObject = createVBScriptRegExObject
End If
getRegExResult = removeLeadingDelimiter(concatObjectItems(getRegExMatches(RegExObject,
SourceString, RegExPattern, isGlobalSearch, isCaseSensitive), Delimiter), Delimiter)
End Function
Private Function getRegExMatches(ByRef RegExObj As Object, _
ByVal SourceString As String, ByVal RegExPattern As String, ByVal isGlobalSearch As Boolean,
ByVal isCaseSensitive As Boolean) As Object
With RegExObj
.Global = isGlobalSearch
.IgnoreCase = Not (isCaseSensitive) 'it is more user friendly to use positive meaning of
argument, like isCaseSensitive, than to use negative IgnoreCase
.Pattern = RegExPattern
Set getRegExMatches = .Execute(SourceString)
End With
End Function
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Private Function concatObjectItems(ByRef Obj As Object, Optional ByVal DelimiterCustom As String =
";") As String
Dim ObjElement As Variant
For Each ObjElement In Obj
concatObjectItems = concatObjectItems & DelimiterCustom & ObjElement.Value
Next
End Function
Public Function removeLeadingDelimiter(ByVal SourceString As String, ByVal Delimiter As String) As
String
If Left$(SourceString, Len(Delimiter)) = Delimiter Then
removeLeadingDelimiter = Mid$(SourceString, Len(Delimiter) + 1)
End If
End Function
Private Function createVBScriptRegExObject() As Object
Set createVBScriptRegExObject = CreateObject("vbscript.RegExp") 'ex.:
createVBScriptRegExObject.Pattern
End Function
Section 43.2: Scripting File System Object
Set createScriptingFileSystemObject = CreateObject("Scripting.FileSystemObject")
Tools> References> Microsoft Scripting Runtime
Associated DLL: ScrRun.dll
Source: Windows OS
MSDN-Accessing Files with FileSystemObject
The File System Object (FSO) model provides an object-based tool for working with folders and files. It
allows you to use the familiar object.method syntax with a rich set of properties, methods, and events to
process folders and files. You can also employ the traditional Visual Basic statements and commands.
The FSO model gives your application the ability to create, alter, move, and delete folders, or to
determine if and where particular folders exist. It also enables you to get information about folders, such
as their names and the date they were created or last modified.
MSDN-FileSystemObject topics: "...explain the concept of the FileSystemObject and how to use it." exceltrick-
FileSystemObject in VBA – Explained
Scripting.FileSystemObject
Section 43.3: Scripting Dictionary object
Set dict = CreateObject("Scripting.Dictionary")
Tools> References> Microsoft Scripting Runtime
Associated DLL: ScrRun.dll
Source: Windows OS
Scripting.Dictionary object
MSDN-Dictionary Object
GoalKicker.com – VBA Notes for Professionals 170
Section 43.4: Internet Explorer Object
Set createInternetExplorerObject = CreateObject("InternetExplorer.Application")
Tools> References> Microsoft Internet Controls
Associated DLL: ieframe.dll
Source: Internet Explorer Browser
MSDN-InternetExplorer object
Controls an instance of Windows Internet Explorer through automation.
Internet Explorer Objec Basic Members
The code below should introduce how the IE object works and how to manipulate it through VBA. I recommend
stepping through it, otherwise it might error out during multiple navigations.
Sub IEGetToKnow()
Dim IE As InternetExplorer 'Reference to Microsoft Internet Controls
Set IE = New InternetExplorer
With IE
.Visible = True 'Sets or gets a value that indicates whether the object is visible or
hidden.
'Navigation
.Navigate2 "http://www.example.com" 'Navigates the browser to a location that might not be
expressed as a URL, such as a PIDL for an entity in the Windows Shell namespace.
Debug.Print .Busy 'Gets a value that indicates whether the object is engaged in a navigation
or downloading operation.
Debug.Print .ReadyState 'Gets the ready state of the object.
.Navigate2 "http://www.example.com/2"
.GoBack 'Navigates backward one item in the history list
.GoForward 'Navigates forward one item in the history list.
.GoHome 'Navigates to the current home or start page.
.Stop 'Cancels a pending navigation or download, and stops dynamic page elements, such as
background sounds and animations.
.Refresh 'Reloads the file that is currently displayed in the object.
Debug.Print .Silent 'Sets or gets a value that indicates whether the object can display
dialog boxes.
Debug.Print .Type 'Gets the user type name of the contained document object.
Debug.Print .Top 'Sets or gets the coordinate of the top edge of the object.
Debug.Print .Left 'Sets or gets the coordinate of the left edge of the object.
Debug.Print .Height 'Sets or gets the height of the object.
Debug.Print .Width 'Sets or gets the width of the object.
End With
IE.Quit 'close the application window
End Sub
Web Scraping
The most common thing to do with IE is to scrape some information of a website, or to fill a website form and
submit information. We will look at how to do it.
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Let us consider example.com source code:
<!doctype html>
<html>
<head>
<title>Example Domain</title>
<meta charset="utf-8" />
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style ... </style>
</head>
<body>
<div>
<h1>Example Domain</h1>
<p>This domain is established to be used for illustrative examples in documents. You
may use this
domain in examples without prior coordination or asking for permission.</p>
<p><a href="http://www.iana.org/domains/example">More information...</a></p>
</div>
</body>
</html>
We can use code like below to get and set information:
Sub IEWebScrape1()
Dim IE As InternetExplorer 'Reference to Microsoft Internet Controls
Set IE = New InternetExplorer
With IE
.Visible = True
.Navigate2 "http://www.example.com"
'we add a loop to be sure the website is loaded and ready.
'Does not work consistently. Cannot be relied upon.
Do While .Busy = True Or .ReadyState <> READYSTATE_COMPLETE 'Equivalent = .ReadyState <> 4
' DoEvents - worth considering. Know implications before you use it.
Application.Wait (Now + TimeValue("00:00:01")) 'Wait 1 second, then check again.
Loop
'Print info in immediate window
With .Document 'the source code HTML "below" the displayed page.
Stop 'VBE Stop. Continue line by line to see what happens.
Debug.Print .GetElementsByTagName("title")(0).innerHtml 'prints "Example Domain"
Debug.Print .GetElementsByTagName("h1")(0).innerHtml 'prints "Example Domain"
Debug.Print .GetElementsByTagName("p")(0).innerHtml 'prints "This domain is
established..."
Debug.Print .GetElementsByTagName("p")(1).innerHtml 'prints "<a
href="http://www.iana.org/domains/example">More information...</a>"
Debug.Print .GetElementsByTagName("p")(1).innerText 'prints "More information..."
Debug.Print .GetElementsByTagName("a")(0).innerText 'prints "More information..."
'We can change the localy displayed website. Don't worry about breaking the site.
.GetElementsByTagName("title")(0).innerHtml = "Psst, scraping..."
.GetElementsByTagName("h1")(0).innerHtml = "Let me try something fishy." 'You have just
changed the local HTML of the site.
.GetElementsByTagName("p")(0).innerHtml = "Lorem ipsum........... The End"
.GetElementsByTagName("a")(0).innerText = "iana.org"
End With '.document
.Quit 'close the application window
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End With 'ie
End Sub
What is going on? The key player here is the .Document, that is the HTML source code. We can apply some queries
to get the Collections or Object we want.
For example the IE.Document.GetElementsByTagName("title")(0).innerHtml. GetElementsByTagName returns a
Collection of HTML Elements, that have the "title" tag. There is only one such tag in the source code. The Collection
is 0-based. So to get the first element we add (0). Now, in our case, we want only the innerHtml (a String), not the
Element Object itself. So we specify the property we want.
Click
To follow a link on a site, we can use multiple methods:
Sub IEGoToPlaces()
Dim IE As InternetExplorer 'Reference to Microsoft Internet Controls
Set IE = New InternetExplorer
With IE
.Visible = True
.Navigate2 "http://www.example.com"
Stop 'VBE Stop. Continue line by line to see what happens.
'Click
.Document.GetElementsByTagName("a")(0).Click
Stop 'VBE Stop.
'Return Back
.GoBack
Stop 'VBE Stop.
'Navigate using the href attribute in the <a> tag, or "link"
.Navigate2 .Document.GetElementsByTagName("a")(0).href
Stop 'VBE Stop.
.Quit 'close the application window
End With
End Sub
Microsoft HTML Object Library or IE Best friend
To get the most out of the HTML that gets loaded into the IE, you can (or should) use another Library, i.e. Microsoft
HTML Object Library. More about this in another example.
IE Main issues
The main issue with IE is verifying that the page is done loading and is ready to be interacted with. The Do While...
Loop helps, but is not reliable.
Also, using IE just to scrape HTML content is OVERKILL. Why? Because the Browser is meant for browsing, i.e.
displaying the web page with all the CSS, JavaScripts, Pictures, Popups, etc. If you only need the raw data, consider
different approach. E.g. using XML HTTPRequest. More about this in another example.
GoalKicker.com – VBA Notes for Professionals 173
Chapter 44: Macro security and signing of
VBA-projects/-modules
Section 44.1: Create a valid digital self-signed certificate
SELFCERT.EXE
To run macros and maintain the security Office applications provide against malicious code, it is necessary to
digitally sign the VBAProject.OTM from the VBA editor > Tools > Digital Signature.
Office comes with a utility to create a self-signed digital certificate that you can employ on the PC to sign your
projects.
This utility SELFCERT.EXE is in the Office program folder,
Click on Digital Certificate for VBA Projects to open the certificate wizard.
In the dialog enter a suitable name for the certificate and click OK.
If all goes well you will see a confirmation:
GoalKicker.com – VBA Notes for Professionals 174
You can now close the SELFCERT wizard and turn your attention to the certificate you have created.
If you try to employ the certificate you have just created and you check its properties
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You will see that the certificate is not trusted and the reason is indicated in the dialog.
The certificate has been created in the Current User > Personal > Certificates store. It needs to go in Local
Computer > Trusted Root Certificate Authorities > Certificates store, so you need to export from the former and
import to the latter.
Pressing the Windows Key+R which will open the 'Run' Window. then Enter 'mmc' in the window as shown
below and click 'OK '.
The Microsoft Management Console will open and look like the following.
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From the File menu, select Add/Remove Snap-in... Then from the ensuing dialog, double click Certificates and then
click OK
Expand the dropdown in the left window for Certificates - Current User' and select certificates as shown below. The
center panel will then show the certificates in that location, which will include the certificate you created earlier:
GoalKicker.com – VBA Notes for Professionals 177
Right click the certificate and select All Tasks > Export:
Export Wizard
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Click Next
the Only one pre-selected option will be available, so click 'Next' again:
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The top item will already be pre-selected. Click Next again and choose a name and location to save the exported
certificate.
GoalKicker.com – VBA Notes for Professionals 180
Click Next again to save the certificate
Once focus is returned to the Management Console.
Expand the Certificates menu and from the Trusted Root Certification Authorities menu, select Certificates.
Right click. Select All Tasks and Import
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Click next and Save to the Trusted Root Certification Authorities store:
Then Next > Finish, now close the Console.
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If you now use the certificate and check its properties, you will see that it is a trusted certificate and you can use it
to sign your project:
GoalKicker.com – VBA Notes for Professionals 183
Chapter 45: VBA Run-Time Errors
Code that compiles can still run into errors, at run-time. This topic lists the most common ones, their causes, and
how to avoid them.
Section 45.1: Run-time error '6': Overflow
Incorrect code
Sub DoSomething()
Dim row As Integer
For row = 1 To 100000
'do stuff
Next
End Sub
Why doesn't this work?
The Integer data type is a 16-bit signed integer with a maximum value of 32,767; assigning it to anything larger
than that will overflow the type and raise this error.
Correct code
Sub DoSomething()
Dim row As Long
For row = 1 To 100000
'do stuff
Next
End Sub
Why does this work?
By using a Long (32-bit) integer instead, we can now make a loop that iterates more than 32,767 times without
overflowing the counter variable's type.
Other notes
See Data Types and Limits for more information.
Section 45.2: Run-time error '9': Subscript out of range
Incorrect code
Sub DoSomething()
Dim foo(1 To 10)
Dim i As Long
For i = 1 To 100
foo(i) = i
Next
End Sub
Why doesn't this work?
foo is an array that contains 10 items. When the i loop counter reaches a value of 11, foo(i) is out of range. This
error occurs whenever an array or collection is accessed with an index that doesn't exist in that array or collection.
Correct code
Sub DoSomething()
Dim foo(1 To 10)
Dim i As Long
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For i = LBound(foo) To UBound(foo)
foo(i) = i
Next
End Sub
Why does this work?
Use LBound and UBound functions to determine the lower and upper boundaries of an array, respectively.
Other notes
When the index is a string, e.g. ThisWorkbook.Worksheets("I don't exist"), this error means the supplied name
doesn't exist in the queried collection.
The actual error is implementation-specific though; Collection will raise run-time error 5 "Invalid procedure call or
argument" instead:
Sub RaisesRunTimeError5()
Dim foo As New Collection
foo.Add "foo", "foo"
Debug.Print foo("bar")
End Sub
Section 45.3: Run-time error '13': Type mismatch
Incorrect code
Public Sub DoSomething()
DoSomethingElse "42?"
End Sub
Private Sub DoSomethingElse(foo As Date)
' Debug.Print MonthName(Month(foo))
End Sub
Why doesn't this work?
VBA is trying really hard to convert the "42?" argument into a Date value. When it fails, the call to DoSomethingElse
cannot be executed, because VBA doesn't know what date to pass, so it raises run-time error 13 type mismatch,
because the type of the argument doesn't match the expected type (and can't be implicitly converted either).
Correct code
Public Sub DoSomething()
DoSomethingElse Now
End Sub
Private Sub DoSomethingElse(foo As Date)
' Debug.Print MonthName(Month(foo))
End Sub
Why does this work?
By passing a Date argument to a procedure that expects a Date parameter, the call can succeed.
Section 45.4: Run-time error '91': Object variable or With
block variable not set
Incorrect code
Sub DoSomething()
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Dim foo As Collection
With foo
.Add "ABC"
.Add "XYZ"
End With
End Sub
Why doesn't this work?
Object variables hold a reference, and references need to be set using the Set keyword. This error occurs whenever
a member call is made on an object whose reference is Nothing. In this case foo is a Collection reference, but it's
not initialized, so the reference contains Nothing - and we can't call .Add on Nothing.
Correct code
Sub DoSomething()
Dim foo As Collection
Set foo = New Collection
With foo
.Add "ABC"
.Add "XYZ"
End With
End Sub
Why does this work?
By assigning the object variable a valid reference using the Set keyword, the .Add calls succeed.
Other notes
Often, a function or property can return an object reference - a common example is Excel's Range.Find method,
which returns a Range object:
Dim resultRow As Long
resultRow = SomeSheet.Cells.Find("Something").Row
However the function can very well return Nothing (if the search term isn't found), so it's likely that the chained
.Row member call fails.
Before calling object members, verify that the reference is set with a If Not xxxx Is Nothing condition:
Dim result As Range
Set result = SomeSheet.Cells.Find("Something")
Dim resultRow As Long
If Not result Is Nothing Then resultRow = result.Row
Section 45.5: Run-time error '20': Resume without error
Incorrect code
Sub DoSomething()
On Error GoTo CleanFail
DoSomethingElse
CleanFail:
Debug.Print Err.Number
Resume Next
End Sub
Why doesn't this work?
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If the DoSomethingElse procedure raises an error, execution jumps to the CleanFail line label, prints the error
number, and the Resume Next instruction jumps back to the instruction that immediately follows the line where the
error occurred, which in this case is the Debug.Print instruction: the error-handling subroutine is executing without
an error context, and when the Resume Next instruction is reached, run-time error 20 is raised because there is
nowhere to resume to.
Correct Code
Sub DoSomething()
On Error GoTo CleanFail
DoSomethingElse
Exit Sub
CleanFail:
Debug.Print Err.Number
Resume Next
End Sub
Why does this work?
By introducing an Exit Sub instruction before the CleanFail line label, we have segregated the CleanFail errorhandling
subroutine from the rest of the procedure body - the only way to execute the error-handling subroutine is
via an On Error jump; therefore, no execution path reaches the Resume instruction outside of an error context,
which avoids run-time error 20.
Other notes
This is very similar to Run-time error '3': Return without GoSub; in both situations, the solution is to ensure that the
normal execution path cannot enter a sub-routine (identified by a line label) without an explicit jump (assuming On
Error GoTo is considered an explicit jump).
Section 45.6: Run-time error '3': Return without GoSub
Incorrect Code
Sub DoSomething()
GoSub DoThis
DoThis:
Debug.Print "Hi!"
Return
End Sub
Why doesn't this work?
Execution enters the DoSomething procedure, jumps to the DoThis label, prints "Hi!" to the debug output, returns to
the instruction immediately after the GoSub call, prints "Hi!" again, and then encounters a Return statement, but
there's nowhere to return to now, because we didn't get here with a GoSub statement.
Correct Code
Sub DoSomething()
GoSub DoThis
Exit Sub
DoThis:
Debug.Print "Hi!"
Return
End Sub
Why does this work?
By introducing an Exit Sub instruction before the DoThis line label, we have segregated the DoThis subroutine from
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the rest of the procedure body - the only way to execute the DoThis subroutine is via the GoSub jump.
Other notes
GoSub/Return is deprecated, and should be avoided in favor of actual procedure calls. A procedure should not
contain subroutines, other than error handlers.
This is very similar to Run-time error '20': Resume without error; in both situations, the solution is to ensure that the
normal execution path cannot enter a sub-routine (identified by a line label) without an explicit jump (assuming On
Error GoTo is considered an explicit jump).
GoalKicker.com – VBA Notes for Professionals 188
Chapter 46: Error Handling
Section 46.1: Avoiding error conditions
When a runtime error occurs, good code should handle it. The best error handling strategy is to write code that
checks for error conditions and simply avoids executing code that results in a runtime error.
One key element in reducing runtime errors, is writing small procedures that do one thing. The fewer reasons
procedures have to fail, the easier the code as a whole is to debug.
Avoiding runtime error 91 - Object or With block variable not set:
This error will be raised when an object is used before its reference is assigned. One might have a procedure that
receives an object parameter:
Private Sub DoSomething(ByVal target As Worksheet)
Debug.Print target.Name
End Sub
If target isn't assigned a reference, the above code will raise an error that is easily avoided by checking if the object
contains an actual object reference:
Private Sub DoSomething(ByVal target As Worksheet)
If target Is Nothing Then Exit Sub
Debug.Print target.Name
End Sub
If target isn't assigned a reference, then the unassigned reference is never used, and no error occurs.
This way of early-exiting a procedure when one or more parameter isn't valid, is called a guard clause.
Avoiding runtime error 9 - Subscript out of range:
This error is raised when an array is accessed outside of its boundaries.
Private Sub DoSomething(ByVal index As Integer)
Debug.Print ActiveWorkbook.Worksheets(index)
End Sub
Given an index greater than the number of worksheets in the ActiveWorkbook, the above code will raise a runtime
error. A simple guard clause can avoid that:
Private Sub DoSomething(ByVal index As Integer)
If index > ActiveWorkbook.Worksheets.Count Or index <= 0 Then Exit Sub
Debug.Print ActiveWorkbook.Worksheets(index)
End Sub
Most runtime errors can be avoided by carefully verifying the values we're using before we use them, and branching
on another execution path accordingly using a simple If statement - in guard clauses that makes no assumptions
and validates a procedure's parameters, or even in the body of larger procedures.
Section 46.2: Custom Errors
Often when writing a specialized class, you'll want it to raise its own specific errors, and you'll want a clean way for
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user/calling code to handle these custom errors. A neat way to achieve this is by defining a dedicated Enum type:
Option Explicit
Public Enum FoobarError
Err_FooWasNotBarred = vbObjectError + 1024
Err_BarNotInitialized
Err_SomethingElseHappened
End Enum
Using the vbObjectError built-in constant ensures the custom error codes don't overlap with reserved/existing
error codes. Only the first enum value needs to be explicitly specified, for the underlying value of each Enum
member is 1 greater than the previous member, so the underlying value of Err_BarNotInitialized is implicitly
vbObjectError + 1025.
Raising your own runtime errors
A runtime error can be raised using the Err.Raise statement, so the custom Err_FooWasNotBarred error can be
raised as follows:
Err.Raise Err_FooWasNotBarred
The Err.Raise method can also take custom Description and Source parameters - for this reason it's a good idea
to also define constants to hold each custom error's description:
Private Const Msg_FooWasNotBarred As String = "The foo was not barred."
Private Const Msg_BarNotInitialized As String = "The bar was not initialized."
And then create a dedicated private method to raise each error:
Private Sub OnFooWasNotBarredError(ByVal source As String)
Err.Raise Err_FooWasNotBarred, source, Msg_FooWasNotBarred
End Sub
Private Sub OnBarNotInitializedError(ByVal source As String)
Err.Raise Err_BarNotInitialized, source, Msg_BarNotInitialized
End Sub
The class' implementation can then simply call these specialized procedures to raise the error:
Public Sub DoSomething()
'raises the custom 'BarNotInitialized' error with "DoSomething" as the source:
If Me.Bar Is Nothing Then OnBarNotInitializedError "DoSomething"
'...
End Sub
The client code can then handle Err_BarNotInitialized as it would any other error, inside its own error-handling
subroutine.
Note: the legacy Error keyword can also be used in place of Err.Raise, but it's obsolete/deprecated.
Section 46.3: Resume keyword
An error-handling subroutine will either:
run to the end of the procedure, in which case execution resumes in the calling procedure.
or, use the Resume keyword to resume execution inside the same procedure.
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The Resume keyword should only ever be used inside an error handling subroutine, because if VBA encounters
Resume without being in an error state, runtime error 20 "Resume without error" is raised.
There are several ways an error-handling subroutine may use the Resume keyword:
Resume used alone, execution continues on the statement that caused the error. If the error isn't actually
handled before doing that, then the same error will be raised again, and execution might enter an infinite
loop.
Resume Next continues execution on the statement immediately following the statement that caused the
error. If the error isn't actually handled before doing that, then execution is permitted to continue with
potentially invalid data, which may result in logical errors and unexpected behavior.
Resume [line label] continues execution at the specified line label (or line number, if you're using legacystyle
line numbers). This would typically allow executing some cleanup code before cleanly exiting the
procedure, such as ensuring a database connection is closed before returning to the caller.
On Error Resume Next
The On Error statement itself can use the Resume keyword to instruct the VBA runtime to effectively ignore all
errors.
If the error isn't actually handled before doing that, then execution is permitted to continue with potentially
invalid data, which may result in logical errors and unexpected behavior.
The emphasis above cannot be emphasized enough. On Error Resume Next effectively ignores all errors and
shoves them under the carpet. A program that blows up with a runtime error given invalid input is a better
program than one that keeps running with unknown/unintended data - be it only because the bug is much more
easily identifiable. On Error Resume Next can easily hide bugs.
The On Error statement is procedure-scoped - that's why there should normally be only one, single such On Error
statement in a given procedure.
However sometimes an error condition can't quite be avoided, and jumping to an error-handling subroutine only to
Resume Next just doesn't feel right. In this specific case, the known-to-possibly-fail statement can be wrapped
between two On Error statements:
On Error Resume Next
[possibly-failing statement]
Err.Clear 'resets current error
On Error GoTo 0
The On Error GoTo 0 instruction resets error handling in the current procedure, such that any further instruction
causing a runtime error would be unhandled within that procedure and instead passed up the call stack until it is
caught by an active error handler. If there is no active error handler in the call stack, it will be treated as an
unhandled exception.
Public Sub Caller()
On Error GoTo Handler
Callee
Exit Sub
Handler:
GoalKicker.com – VBA Notes for Professionals 191
Debug.Print "Error " & Err.Number & " in Caller."
End Sub
Public Sub Callee()
On Error GoTo Handler
Err.Raise 1 'This will be handled by the Callee handler.
On Error GoTo 0 'After this statement, errors are passed up the stack.
Err.Raise 2 'This will be handled by the Caller handler.
Exit Sub
Handler:
Debug.Print "Error " & Err.Number & " in Callee."
Resume Next
End Sub
Section 46.4: On Error statement
Even with guard clauses, one cannot realistically always account for all possible error conditions that could be raised
in the body of a procedure. The On Error GoTo statement instructs VBA to jump to a line label and enter "error
handling mode" whenever an unexpected error occurs at runtime. After handling an error, code can resume back
into "normal" execution using the Resume keyword.
Line labels denote subroutines: because subroutines originate from legacy BASIC code and uses GoTo and GoSub
jumps and Return statements to jump back to the "main" routine, it's fairly easy to write hard-to-follow spaghetti
code if things aren't rigorously structured. For this reason, it's best that:
a procedure has one and only one error-handling subroutine
the error-handling subroutine only ever runs in an error state
This means a procedure that handles its errors, should be structured like this:
Private Sub DoSomething()
On Error GoTo CleanFail
'procedure code here
CleanExit:
'cleanup code here
Exit Sub
CleanFail:
'error-handling code here
Resume CleanExit
End Sub
Error Handling Strategies
Sometimes you want to handle different errors with different actions. In that case you will inspect the global Err
object, which will contain information about the error that was raised - and act accordingly:
CleanExit:
Exit Sub
CleanFail:
Select Case Err.Number
Case 9
MsgBox "Specified number doesn't exist. Please try again.", vbExclamation
GoalKicker.com – VBA Notes for Professionals 192
Resume
Case 91
'woah there, this shouldn't be happening.
Stop 'execution will break here
Resume 'hit F8 to jump to the line that raised the error
Case Else
MsgBox "An unexpected error has occurred:" & vbNewLine & Err.Description, vbCritical
Resume CleanExit
End Select
End Sub
As a general guideline, consider turning on the error handling for entire subroutine or function, and handle all the
errors that may occur within its scope. If you need to only handle errors in the small section section of the code --
turn error handling on and off a the same level:
Private Sub DoSomething(CheckValue as Long)
If CheckValue = 0 Then
On Error GoTo ErrorHandler ' turn error handling on
' code that may result in error
On Error GoTo 0 ' turn error handling off - same level
End If
CleanExit:
Exit Sub
ErrorHandler:
' error handling code here
' do not turn off error handling here
Resume
End Sub
Line numbers
VBA supports legacy-style (e.g. QBASIC) line numbers. The Erl hidden property can be used to identify the line
number that raised the last error. If you're not using line numbers, Erl will only ever return 0.
Sub DoSomething()
10 On Error GoTo 50
20 Debug.Print 42 / 0
30 Exit Sub
40
50 Debug.Print "Error raised on line " & Erl ' returns 20
End Sub
If you are using line numbers, but not consistently, then Erl will return the last line number before the instruction that
raised the error.
Sub DoSomething()
10 On Error GoTo 50
Debug.Print 42 / 0
30 Exit Sub
50 Debug.Print "Error raised on line " & Erl 'returns 10
End Sub
Keep in mind that Erl also only has Integer precision, and will silently overflow. This means that line numbers
GoalKicker.com – VBA Notes for Professionals 193
outside of the integer range will give incorrect results:
Sub DoSomething()
99997 On Error GoTo 99999
99998 Debug.Print 42 / 0
99999
Debug.Print Erl 'Prints 34462
End Sub
The line number isn't quite as relevant as the statement that caused the error, and numbering lines quickly
becomes tedious and not quite maintenance-friendly.
GoalKicker.com – VBA Notes for Professionals 194
Credits
Thank you greatly to all the people from Stack Overflow Documentation who helped provide this content,
more changes can be sent to web@petercv.com for new content to be published or updated
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