1. VBA - Excel VBA is Visual Basic for Applications
The goal is to demonstrate how VBA can be used to leverage the power of Excel in designing a student data form.
VBA syntax and usage
the Excel VB programming environment
the Excel object model
student data form application

2. What advantage is there in using VBA
VBA - Excel
What advantage is there in using VBA
extend Excel – new functions
makes it possible to use the Excel GUI environment
makes it possible to respond to events (mouse, …)
makes Windows programming API accessible

3. VBA – The Basics Data types Integer 2 byte integer Long 4 byte integer
Single 4 byte floating point
Double 8 byte floating point
Currency 8 byte real
String up to 64K characters
Byte 1 byte
Boolean 2 byte true or false
Date 8 bytes
Object 4 bytes – an object reference
Variant 16 bytes + 1 byte / character

4. VBA – The Basics .Variables
must start with a letter
can contain _ and numbers
cannot exceed 255 characters in length
Within a procedure declare a variable using
VBA variables have scope restrictions
variables declared in a procedure are local to that procedure
variables declared in a module can be public or private
Dim variable
Dim variable As type

5. The first form is variable length
VBA – The Basics
String variables
The first form is variable length
The second form is limited to 50 characters
the variable will be space filled if string is < 50 characters
the string will be truncated if the contents are > 50 characters
the Trim and RTrim functions are useful for working with fixed length strings
Boolean variables contain either True or False
Dim variable As String
Dim variable As String * 50

6. VBA – The Basics
The Object type is used to store the address (a reference) of an object
this form can be used for any object
this is referred to as late-binding, the object types are checked at runtime (slower)
The declaration of a specific object is
this form will only store Excel Worksheet objects, an attempt to put anything else into it will result in an error
this is referred to as early-binding, the object types are checked at compile time (faster)
Dim variable As Object
Dim variable As Worksheet

7. VBA – The Basics Arrays are declared using
Arrays can be multidimensional
The lower bound starts at zero
can explicitly specify lower bound
can use Option Base command to reset to something other than 0
The last form above is a dynamic array – it must be dimensioned using ReDim before it can be used
Use ReDim Preserve to retain any existing entries in array - only the upper bound of array can be changed
Dim A (1 To 10) As Double
Dim B (1 To 10, 1 To 10) As Double
Dim C (4,4,4) As Integer
Dim D () As Double
Option Base 1

8. VBA – The Basics Constants are declared using
Constants have the same scope limitations as variables
Const pi =
Const pi As Double =

9. VBA – The Basics User defined data types
can only be defined in the declarations section of a Module
can be Public or Private in scope
Declare variable with this type
Referencing fields
Public Type SystemInfo
CPU As Variant
Memory As Long
ColorBits As Integer
Cost As Currency
PurchaseDate As Date
End Type
Dim MySystem As SystemInfo
MySystem.CPU = “Pentium”
If MySystem.PurchaseDate > #1/1/2006# Then …
End If

10. VBA – The Basics Watch out for it is equivalent to
Dim a, b, c As Integer
Dim a As Variant
Dim b As Variant
Dim c As Integer

11. VBA – The Basics Objects
VBA can use pre-defined objects – such as intrinsic Excel objects
VBA can create user-defined objects – Class Modules
Declaring a variable to contain an object
the first form declares that the variable will contain a reference to an object of the named class
the second form declares the variable then creates an instance of the class
To instantiate a class
Dim variable As class
Dim variable As New class
Set variable = New class

12. VBA – The Basics Objects
To declare a variable that will refer to an instance of the Excel Worksheet class
To put a reference into it
This fragment will print the name of the worksheet “Sheet1”
Dim ws1 As Worksheet
Set ws1 = Worksheets(“Sheet1”)
Dim ws1 As Worksheet
Set ws1 = Worksheets("sheet1")
Debug.Print ws1.Name

13. VBA – The Basics Objects - Collections
There is a special form of objects known as Collections
They contain references to other objects and collections
It is the mechanism by which the object hierarchy is defined
By convention, collection names are usually plural
Workbooks – list of Workbook objects
Worksheets – list of Worksheet objects
Range – list of objects that represent cells, columns, rows
The following example iterates through Workbooks collection
For Each ws In Worksheets
Debug.Print ws.Name
Next

14. VBA – The Basics Statements
VBA implements common programming statements
logical statements
looping statements
expressions

15. VBA – The Basics Logical statements
The If Then Else statement is the basic logic test
If a>10 Then …
End If
If a>10 Then …
Else
End If
If a>10 Then …
ElseIf a<0 Then
Else
End If

16. VBA – The Basics Logical statements
The Select statement can be used to replace a multi-way if statement
Select Case expression
Case expr1 …
Case expr2
Case Else
End Select

17. VBA – The Basics Loop statements Various Do loop forms Do Until expr
Do While expr …
Loop
Do Until expr …
Loop Do …
Loop While expr Do …
Loop Until expr

18. VBA – The Basics Loop statements A common For loop For i=1 To 10
Debug.print i
Next i
For i=1 To 10 Step 2
Debug.print i
Next i

19. VBA – The Basics Loop statements Another For loop
Commonly used to iterate through collections
For Each element In group …
Next element
For Each ws In Worksheets
Debug.Print ws.Name
Next

20. VBA – The Basics Procedures
Procedures in VBA are either Macros or Functions
a macro does not return a value
a function will return a value
Property functions (Get and Let) are used in Class Modules to provide access to private properties
Sub Name() …
End Sub
Function Name() As Double …
End Sub

21. VBA – The Basics Dealing with runtime errors
The On Error statement will trap errors
The error name is a label in the code
In the error code a Resume statement will cause the statement that caused the error to be executed again
In the error code a Resume Next statement will restart execution on the statement after the one that caused the error …
On Error GoTo label …
On Error GoTo check
check:

22. VBA – Programming Environment
Excel (all Office components) have a VBA programming environment, VBIDE
It consists of
the Visual Basic Editor
an Object Browser
debugging support

23. VBA – Programming Environment
To start the Visual Basic Editor from Excel select
Developer | Visual Basic

24. VBA Environment

25. VBA – Programming Environment
Once in the VB Editor – to start the Object Browser select
View | Object Browser

26. VBA – Programming Environment
In the Object Browser to select only the Excel objects use the pull down menu at the upper left

27. VBA – Programming Environment
To view information on the Worksheet object and its Name property

28. VBA – Programming Environment
The usual way to create code is to double-click on one of the Worksheet or Workbook objects in the Project Explorer and enter the code.

29. VBA – Programming Environment
By using the menu item Insert it is possible to add other types of procedure containers
forms (GUI)
modules for library-like procedures
class modules for defining classes

30. VBA – Excel Objects
Excel exposes all of its functionality through objects
These are directly accessible to the VBA programmer
They are also visible to other applications through COM Automation
matlab
scripting languages
other Office components

31. Student database management system using Excel
VBA – An Example
Student database management system using Excel

32. VBA – An Example
A view from the Visual Basic Editor