VBA & Excel

Barry L. Nelson

IEMS 465

Fall Quarter 2003

VBA

• Is a significant subset of the stand-alone Visual Basic programming language

• It is integrated into Microsoft Office applications (and others, like Arena)

• It is the macro language of Excel• You can add

– Forms for dialog boxes with user– Classes for object definitions– Modules containing procedures

Accessing VBA in Excel

• Tools Macros Visual Basic Editor

• Enter VBA through the navigation buttons in the top toolbars

VBA Design Mode

Visual Basic Editor

Design mode is the time during which no code from the project is running and events from Excel or project will not execute. You can leave design mode by executing a macro or using the Immediate window.

VB Edit Window

Project Explorer

Property Inspector

Code Window

Edit Window Options

Variables

• Declare by Dim

• Better to use Data Types:Dim amount As DoubleDim year As IntegerDim name As String

• Other data types: Boolean, Byte, Currency, Date

• Default (no type) is Variant

Variable(cont’d.)

• % - integer & - long integer! - single # - double@ currency$ - stringanIntegerValue% =3, aString$ = "hallo"

• Can modify with scope (outside procedure)Private I As IntegerPublic billsPaid As Currency

• Make values permanentStatic yourName As String

• Multiple variablesPrivate test, amount, J As Integer

Constants

• [Public|Private] Const constantName [As type] = expression

Public Const PI = 3.1, NumPLANETS = 9Const PI2 = PI * 2Const RELEASE = #1/1/99/#

Control Structures

• DecisionIf anyDate < Now Then anyDate =

Now

If anyDate < Now ThenanyDate = Now

End If

If … Then … Else

Decisions(cont’d.)

If Index = 0 ThenCopyActiveControlClearActiveControl

Else If Index = 1 ThenCopyActiveControl

Else If Index = 2 ThenClearActiveControl

ElsePasteActive Control

End If

Decisions(cont’d.)

Select Case IndexCase 0

CopyActiveControlClearActiveControl

Case 1CopyActiveControl

Case 2ClearActiveControl

Case 3PasteActive Control

Case ElsefrmFind.Show

End Select

Loops/Iterations

• Do … LoopDo While condition

statementsLoop

Dostatements

Loop While condition

Loops(cont’d.)

• For … NextFor counter = start To end [Step increment]

statements Next counter

• For Each … NextFor Each element In group

statementsNext element

Exiting Control Structures

For counter = start To end [Step increment][statement block][Exit For][statement block]

Next [counter [, counter][, …]]

Do [ {While|Until} condition]

[statement block][Exit Do][statement block]

Loop

Exiting(cont’d.)

• Can also exit from a procedure:

Exit Sub

Code Modules

• Excel Objects (ThisWorkbook, Sheet#)

• Modules– Typically we put our code here– A Module is a collection of Subs and

Functions– Insert Module

• Class Modules

• User Forms

Procedures

• Sub (routines)– no value returned– Called without parenthesis

mySub param1, param2– Called with parenthesis

Call mySub(param1, param2)

• Functions– value returned– assign return value to function name

Arguments for Procedures

• Pass by Reference (default)sub stuff(item As String) ‘or sub stuff(ByRef item As String)…stuff(“car”)

• Pass by Value (must be declared)sub stuff(ByVal item As String)

• Note that arguments must be formally declared (as must the return type of functions)

Some Useful Code

• The following are some pieces of code that are useful for doing VBA with Excel.

• See the code on the course web site for other examples.

Finding/Creating a Sheet Dim found As Boolean Dim sheetNext As Worksheet ' Set up mySheet sheet for output found = False For Each sheetNext In Worksheets If sheetNext.Name = “mySheet" Then found = True Exit For End If Next sheetNext If found = True Then Worksheets(“mySheet").Select ActiveSheet.UsedRange.Clear Else Worksheets.Add ActiveSheet.Name = “mySheet" End If

Writing to a Sheet

• Put the absolute value of the variable Fudge in row 2, column 20 of the Sheet named mySheet.

Worksheets(“mySheet”).Cells(2,20) = VBA.Abs(Fudge)

Use an Excel Function

• VBA has a limited number of built-in functions

• You can access any Excel worksheet function.

• This example uses the Excel Max function

W = WorksheetFunction.Max(0, W + S - a)

Running the Code

• Perhaps the easiest way to run the code is to place your cursor in the module you want to run and press the Run Sub/UserForm button.

• Your modules will as appear as Macros that can be run from Excel under

Tools Macros Macros…

Finishing Up

• Explore what is available in the IEMS 465 code

• Exercise: Write a Sub that inserts a worksheet named “Count” into the Workbook, then writes the numbers 1,2,…,10 in the first row, the first ten columns. Use a loop to do this.