Introduction to Computing Dr. Nadeem A Khan

Lecture 24

► The general format with step of 1: For i = m To n Statements Next i For…Next Loops

► Convert to For.. Next Loop Sub Command1_Click ( ) Dim num As Integer Let num=1 Do While num<=10 Picture1.Print num; Let num=num+1 Loop End Sub For Next Loops

► Example with For.. Next Loop Sub Command1_Click ( ) Dim num As Integer For num=1 To 10 Picture1.Print num; Next num End Sub For Next Loops

► The result: For Next Loops

► The general format with steps: For i = m To n Step s Statements Next i => Each time increment: i = i + s; m, n, s could be numeric expressions m, n, s could be numeric expressions For…Next Loops

► Example with For.. Next Loop with steps Sub Command1_Click ( ) Dim num As Integer For num= 1 To 10 Step 2 Picture1.Print num; Next num End Sub The output? For Next Loops

► The result: For Next Loops

► Rewrite the following program using nested For.. Next Loop Nested Loops: For…Next

Sub Command1_Click ( ) Dim num As Integer, counter As Integer Let counter=1 Do While counter<=4 Let num=1 Let num=1 Do While num<=10 Picture1.Print num; Let num=num+1 Loop Let counter=counter+1 Picture1.PrintLoop End Sub Nested Loops: For…Next

Sub Command1_Click ( ) Dim num As Integer, counter As Integer For counter = 1 To 4 For num =1 To 10 For num =1 To 10 Picture1.Print num; Next num Picture1.Print Next counter End Sub Nested Loops: For…Next

► The result: Nested Loops

► Reverses the input string Sub Command1_Click ( ) Picture1.Cls Picture1.Print Reverse$((Text1.Text)) End Sub For Next Loops

Function Reverse$ (info As String) Dim m As Integer, j As Integer, temp As String Let temp = “” For j = Len(info) To 1 Step -1 Let temp = temp + Mid$(info, j, 1) Next Reverse$ = temp End Function For Next Loops

► Exit For: Works similar as Exit Do Exit For

Note: ► Read: Schneider Chapter 6, Warner Chapter 6 ► Read comments and do practice problems of these sections of these sections ► Attempt some questions of Exercises

Chapter 7: Array Variables (Arrays)

► Array:  A list of values can be assigned  Collection of variables of the same type Array Variables (Arrays)

► Array Declaration: Dim arrayName (1 to n) As varType e.g: Dim names(1 To 3) as Strings Dim scores(1 To 10) as Single Array Variables (Arrays)

► Value assignment: Dim names(1 To 3) as Strings Let names(1)=“Aslam” Let names(2)=“Khalid” Let names(3)=“Akbar” Picture1.Print names(3), names(2),names(1) Array Variables (Arrays)

► What is what? Dim scores(1 To 3) as Single scores( ): name of the array scores(1): first element scores(2): second element scores(3): third element 1, 2, 3: subscripts Array Variables (Arrays)

► What are the ranges or dimensions? Dim scores(1 To 3) as Single Dim names(1 To 10) as String Array Variables (Arrays)

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