2 Visual Basic 6.0

2.7

2.7.1

2-6

Private Sub Command1_Click() Dim x, y As Double Const a = 3 Const b = -5 x = Val(Text1.Text) y = a * x ^ 2 + b * x + 1 y = y / Abs(a + b) Text2.Text = Str$(y)End Sub

2.7.2 Visual Basic 6.0 IfThen IfThenElse Iif Select Case

1IfThenIf Then If Then []End IfVisual Basic 6.0 TrueFalseFalseTrueTrueVisual Basic 6.0Then

2 IfThenElseIf 1 Then [1][Else If 2 Then [2]] ...[Else [n]]End IfVisual Basic 6.01FalseVisual Basic 6.02TrueTrueVisual Basic 6.0End IfElsen-1FalseVisual Basic 6.0Else

3IIfIIf()

4Visual Basic 6.0Select CaseIfThenElseSelect CaseIfThenElseSelect CaseSelect CaseVisual Basic 6.0CaseCaseSelect Case test [Case 1 [1]] [Case 2 [2]] ... [Case Else [n]]End Select

2-7

Private Sub Command1_Click() Dim a As Integer' a = Val(Text1.Text)'a If a < 0 Then'a a = -a End If Text2.Text = Str$(a)End Sub

Private Sub Command2_Click() Text1.Text = "" Text2.Text = ""End Sub

2-8

Private Sub Command1_Click() Dim x As Integer x = Val(Text1.Text) If (x Mod 100) Then'X100 If (x Mod 4 = 0) Then'x4100 Text2.Text = "yes" Else'x4100 Text2.Text = "no" End If ElseIf (x Mod 400 = 0) Then'x100400 Text2.Text = "yes" Else Text2.Text = "no" End IfEnd Sub

Private Sub Command2_Click() Text1.Text = "" Text2.Text = ""End Sub

2-9

Case 6 Text2.Text = "" Case 7 Text2.Text = "" Case 8 Text2.Text = "" Case 9 Text2.Text = "" Case 10 Text2.Text = "" Case 11 Text2.Text = "" Case 0 Text2.Text = "" End SelectEnd SubPrivate Sub Command1_Click() Dim year As Integer, a As Integer year = Val(Text1.Text) a = year Mod 12 Select Case a Case 1 Text2.Text = "" Case 2 Text2.Text = "" Case 3 Text2.Text = "" Case 4 Text2.Text = "" Case 5 Text2.Text = ""

ElseIf a=6 Then Text2.Text = "" ElseIf a=7 Then Text2.Text = "" ElseIf a=8 Then Text2.Text = "" ElseIf a=9 Then Text2.Text = "" ElseIf a=10 Then Text2.Text = "" ElseIf a=11 Then Text2.Text = "" Else Text2.Text = "" End IfEnd SubIfThenElsePrivate Sub Command1_Click() Dim year As Integer, a As Integer year = Val(Text1.Text) a = year Mod 12 If a=1 Then Text2.Text = "" ElseIf a=2 Then Text2.Text = "" ElseIf a=3 Then Text2.Text = "" ElseIf a=4 Then Text2.Text = "" ElseIf a=5 Then Text2.Text = ""

2.7.3 DoLoop ForNext

1DoLoop DoDoLoopIfThen TrueFalseDoLoopTrueDo While () []Loop Visual Basic 6.0DoFalseTrueVisual Basic 6.0Do WhileTrueFalse

DoLoopDo []Loop While () FalseTrue

2ForNext DoForForFor = To [Step ] []Next [] Step1= +

For Visual Basic 6.0 Next []= +

2-10 121%20

Private Sub Form_Click() Dim a As Double Dim r As Single Dim i As Integer a = 12 r = 0.01 i = 0 Do While a < 20 '20 a = a * (1 + r) i = i + 1 Loop Print i ;"20"End SubDoLoop WhilePrivate Sub Form_Click() Dim a As Double Dim r As Single Dim i As Integer a = 12 r = 0.01 i = 0 Do a = a * (1 + r) i = i + 1 Loop While a < 20 '20 Print i "20"End Sub

2-11 m=1+2+3+4+100

Private Sub Form_Click() Dim m As Integeri As Integer m = 0 For i = 1 To 100'1 m = m + i Next i Print mEnd Sub

2.7.4

1 ForNextIfThennestVisual Basic 6.0

2 ExitForDoFor = To [Step ] [] [Exit For] []Next [[, ] [,]]Do [{While | Until} ] [] [Exit Do] [] Loop Exit DoDoExit ForExit Do

2-12 121%20

Private Sub Form_Click() Dim a As Double Dim r As Single Dim i As Integer a = 12 r = 0.01 For i=0 to 1000 a = a * (1 + r) If a >= 20 Then Exit For '20 Next i Print i; "20"End Sub

2.8 Visual Basic 6.0S(i) SiS(8)S

2.8.1 3 Public Private Private

Long-2 147 483 648~2 147 483 647Dim A(4) As Integer 'A(0)A(1)A(2)A(3)A(4)5Dim S (20) As Double 'S(0)S(20)21PublicDimPublic A(4) As IntegerPublic S (20) As Double 50421020

ToLongDim A (1 To 5) As IntegerDim S (100 To 120) As StringA1~5S100~120

LboundUboundLbound() 'Ubound() '

2.8.2 Visual Basic 6.0

1PublicDimStaticDimDim A ()

2ReDimReDim A (X + 1)ReDimDimStaticReDimReDimReDim

2.8.3 Visual Basic 6.0For EachNext

1Number(1)A(2)Num(0)B(4)

213For i=1 to 5 A(i)=3Next i

2Array()ArrayStatic Number Number=Array(1,2,3,4,5) Array()Varient 0Option BaseArray()UBound() Array()

41Dim b(4),a(6)b(2)=a(3)2For

3Dim a(4) as integer,b() as integerA(0)=0:a(1)=5:a(2)=10:a(3)=13:a(4)=14B=a

5For EachNextFor EachNextForNextForNextFor EachNextFor Each In []Next []

For EachNext

2-13

Private Sub Form_Click() Dim a(), b() ' a = Array(1, 2, 3, 4, 5) ' ReDim b(UBound(a)) ' For i = 0 To UBound(a) ' b(i) = a(i) Next i For i = 0 To UBound(a) ' Print b(i); Next iEnd Sub

2-14 A

Private Sub Form_Click() Dim sum As Integer Dim A(1 To 10) As Integer ' For i = 1 To 10 ' A(i) = 1 Next i sum = 0 For Each x In A 'For EachNext sum = sum + x Next x Print sum 'End Sub

2-15 Option Base 1Private Sub Form_Click() Dim abc(10) As Integer ' For i = 1 To 10 '0~100 abc(i) = Int(Rnd * 100) Next i Print "" For i = 1 To 10 ' Print abc(i); Next i Print Print "For EachNext" For Each x In abc 'For EachNext Print x; NextEnd Sub

2.9 12

2.9.1 Visual Basic

1Visual Basic 6.0SubFunction

2

Private Sub _ ( ) End SubPrivate Sub Form_ () End Sub

2.9.2 Sub1[Private | Public][Static] Sub [] [Exit Sub] End Sub

2Sub

2-16 Sub

/Dim area As SingleSubSubSub recarea(rlen, rwid) area = rlen * rwidEnd Sub

Private Sub Command1_Click() Dim a As Single, b As Single a = Val(Text1.Text) b = Val(Text2.Text) recarea a, b 'Call recarea(a, b) Text3.Text = areaEnd SubPrivate Sub Command2_Click() Text1.Text = "" Text2.Text = "" Text3.Text = ""End Sub

2-17 TriangleForm_Click

Private Sub triangle(Str As String, n As Integer) Dim i As Integer, j As Integer For i = l To n Print Tab(16 - i); For j = 1 To 2 * i - 1 Print Str; Next j Print Next iEnd Sub

Private Sub Form_Click() Dim char As String * 1, n As Integer char = "*" n = 5 Call triangle(char, n) char = "+" triangle char, 3End Sub

2.9.3 FunctionVisual Basic 6.0SqrCosChrFunctionFunctionSubFunctionFunction

1Function[Static] [Public | Private] Function [][As]

=[Exit Function]End Function As Sub

2FunctionSubFunctionSubFunction

3Function Visual Basic 6.0CosTxtPrint 10 * TxtX = TxtIf Txt = 10 Then Print "Out of Range";" X = ";10 * TxtSubCall Sin(x)Sin x

2-18 Function

FunctionFunction recarea(rlen, rwid) As Single recarea = rlen * rwidEnd Function

Private Sub Command1_Click() Dim a As Single, b As Single a = Val(Text1.Text) b = Val(Text2.Text) Text3.Text = Str(recarea(a, b))End Sub

Private Sub Command2_Click() Text1.Text = "" Text2.Text = "" Text3.Text = ""End Sub

2.9.4 SubFunctionVisual Basic 6.0(ByRef)(ByVal)

1ByVal

2Visual Basic 6.0ByVal

3

2-19 Private Sub Increase(x As Integer) x = x + 1End Sub

Private Sub Decrease(ByVal x As Integer) x = x - 1End Sub

Private Sub Form_Click() Dim i As Integer, j As Integer i = 1000 Increase i Print i j = 1000 Decrease j Print jEnd Sub

2.10 Visual Basic 6.0Visual Basic 6.0Visual Basic 6.0

2.10.1 ModuleVisual Basic 6.03

2.10.2 Visual Basic 6.0

2.11

Public Function Sushu(ByVal x As Integer) Dim k, i As Integer k = Int(Sqr(x)) i = 2 Sushu = 0 Do While i

Dim a(0 To 20) As IntegerDim j, m, n As IntegerPrivate Sub Command1_Click() Command2.Enabled = True FontSize = 24 ' Print ' Print "20" For j = 1 To 20 a(j) = CInt(Rnd * 100) '100 Print a(j); ' If j Mod 5 = 0 Then '5 Print End If Next jEnd Sub

Private Sub Command2_Click() n = 0 Print "" For j = 1 To 20 m = Sushu(a(j)) 'a(j) If m = 0 Then ' Print a(j); n = n + 1 End If If n Mod 5 = 0 And n 0 Then '5 n = 0 Print End If Next jEnd Sub

2.12