Introduction to Computing Dr. Nadeem A Khan

Lecture 21

IF BLOCK EXTENDED IF condition 1 Then action1 ElseIf condition 2 Then action 2 action 2 ElseIf condition 3 Then action 3 Else action 4 End If

Select Case Blocks

► Example: Sub Command1_Click ( ) Picture1.Cls Let num = Val(Text1.Text) Select Case num Case 1 Picture1.Print “Buckle my shoe.” Case 2 Picture1.Print “Pick the sticks.” Case 3,4,5,6 Picture1.Print “Lay them straight.” Case Else Picture1.Print “Start all over again.” End Select End Sub

Select Case Block ► General form Select Case selector Case valueList1 action1 Case valueList2 action2.. Case Else action of last resort End Select

Select Case Block (Contd.) ► See fig. 5.4:Flow Chart for Select Case block block

Another example

Sub Command1_Click ( ) Sub Command1_Click ( ) Dim x As Integer, y As Integer, num As Integer Let x=2 Let y=3 Let num = Val(Text1.Text) Select Case num Case y-x, x Picture1.Print “Buckle my shoe.” Case Is<=4 Picture1.Print “Pick up sticks.” Case x+y To x*y Picture1.Print “Lay them straight.” Case Else Picture1.Print “Start all over again.” End Select End Sub

Still another example

Sub Command1_Click ( ) Dim season As string Rem Determine the number of days in a season Picture1.Cls Let season = Text1.Text Picture1.Print season; “has”; NumDays(season);“days.” End Sub Select Case Block (Contd.)

Function NumDays (seasons As String) As Integer Select Case UCase$(season) Case “WINTER” NumDays = 87 Case “SPRING” NumDays = 92 Case “SUMMER”, “AUTUMN”, “FALL” NumDays = 93 End Select End Functions Select Case Block (Contd.)

► Study chapter 5 with all its comments and examples. Solve some problems as well! Note: