Visual Basic for Applications

Companion slides to http://blip.tv/file/3011639

© The Stanford Decisions and Ethics Center

decision.stanford.edu

On our agenda for today…

• Visual Basic for Applications

Buttons and Macros

• Lets create a simple button

Debugging

• MsgBox

• Debug.print (Immediate Window – Ctrl+G)

Iteration Logic

• While Loops Dim MyArray(5) As Double For I = 1 To 5 MyArray(I) = Rnd Next I For Each n In MyArray Debug.Print n Next n

Array Indexing Starts from 1

Iteration Logic

• While-Wend Loops

Dim MyArray(5) As Double I = 0

While i<5 MyArray(I) = Rnd

I = I+1 Wend For Each n In MyArray Debug.Print n Next n

Iteration Logic

• Do While

Do While conditionblah blah

Loop

Doblah blah

Loop While condition

Iteration Logic

• Do Until

Do Until conditionblah blah

Loop

Doblah blah

Loop Until condition

Conditional Logic

• Simple Conditionals

If condition_holds Then Do_something

Conditional Logic

• Nested Conditionals

If condition_holds Then Do_something

ElseIf another_condition_holds Then Do_something_else

End If

Conditional Logic

• More Nesting

If condition_holds Then Do_something

ElseIf another_condition_holds Then Do_something_else

ElseIf another_condition_holds Then Do_something_else

Else do_some_default_thing

End If

Example

• Armstrong Numbers

• Sum of the cubes of the Armstrong number = number itself

E.g. 153

1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153

Reading and Writing

• From and to cells

• From and to cells in different worksheets

Functions and Subroutines

Sub Blah()

End Sub

Function Blah()

Blah = …

End Function

Refactoring

Any fool can write code that a computer

understands. Only a good programmer

can write code that a human understands.

Martin Fowler, in his classic, Refactoring

Refactoring

is changing design without changing functionality

Important refactorings for VBA• Decompose into Small Sub/Functions• Rename to use Intention-Revealing Names

Main MotivationONCE and ONLY ONCE

Getting Inputs

Dim Quantity As Variant Dim Discount As Double Quantity = InputBox("Enter Quantity: ") If Quantity = "" Then Exit Sub If Quantity >= 0 Then Discount = 0.1 If Quantity >= 25 Then Discount = 0.15 If Quantity >= 50 Then Discount = 0.2 If Quantity >= 75 Then Discount = 0.25 MsgBox "Discount: " & Discount

Select Case Dim Quantity As Variant Dim Discount As Double Quantity = InputBox("Enter Quantity: ") Select Case Quantity Case "" Exit Sub Case 0 To 24 Discount = 0.1 Case 25 To 49 Discount = 0.15 Case 50 To 74 Discount = 0.25 End Select MsgBox "Discount: " & Discount

Reffering to cells

Range(“name”).Value = NewValueRange(“A5”).value = …

Cells(..,..).Offset(..,..).ValueActiveCell.Offset(..,..).ValueRange(“..”).Offset(..,..).Value

ActiveSheet.Cells.ClearContents

Getting VBA Help

• Make sure the Help for VBA module is installed when installing Excel 2003

• Use ObjectBrowser

Book on VBA