枚举结构（二）——选择结构和循环结构复习课件（15张幻灯片）

课件15张PPT。VB复习（二） ———选择语句和循环语句单击此处添加标题Part 4选择语句01格式1：行If语句1、If 条件表达式　Then　语句 2、If 条件表达式　Then　语句1　Else　语句2格式2：块If语句If　条件表达式1　Then 　　　语句块1 ElseIf　条件表达式2　　Then 　　语句块2 　�———�… ElseIf　条件表达式n　　Then 　　语句块n Else 　　语句块0 End If1、If 条件表达式　Then　语句 2、If 条件表达式　Then　语句1　Else　语句2If　条件表达式1　Then 　　　语句块1 ElseIf　条件表达式2　　Then 　　语句块2 　�———�… ElseIf　条件表达式n　　Then 　　语句块n Else 　　语句块0 End If格式1：行If语句格式2：块If语句怎么区分行If语句和块If语句？格式1：行if语句 Private Sub Command1_Click() Dim x As Single, y As Single x = Val(Text1.Text) --_____ Label5.Caption = " y=" + Str(y) End SubIf x<0 Then y=x+1 Else y=2*x+3格式2：块if语句 Private Sub Command2_Click() Dim x As Single, y As Single x = Val(Text1.Text) _____ _____ _____ _____ _____ Label5.Caption = " y=" + Str(y) End SubIf x<0 Then y=x+1 Else y=2*x+3 End IfPrivate Sub Command1_Click() Dim x As Single, y As Single x = Val(Text1.Text) If _____ Then y = 1 _____ y = x ^ 2 + 3 Else y = _____ _____ Label5.Caption = "计算结果为：y=" + Str(y) End Sub0<=x And x<1ElseIf x<0 Then5*x+3End If循环语句02For 循环变量 = 初值　To　终值　Step　步长 语句块 Next 循环变量Do　While　条件表达式 　　语句块 Loop格式1：For语句格式2：Do语句方法1：For语句 Private Sub Command1_Click() Dim s As Integer, i As Integer _____ _____ _____ Label2.Caption = "用for语句计算s=" + Str(s) End Sub方法2：Do语句 Private Sub Command2_Click() Dim s As Integer, i As Integer i = _____ Do While _____ _____ _____ _____ Label2.Caption = "用do语句计算s=" + Str(s) End SubFor i=1 To 11 Step 2Next is=s+i方法1：For语句 Private Sub Command1_Click() Dim s As Integer, i As Integer _____ _____ _____ Label2.Caption = "用for语句计算s=" + Str(s) End Sub方法2：Do语句 Private Sub Command2_Click() Dim s As Integer, i As Integer i = _____ Do While _____ _____ _____ _____ Label2.Caption = "用do语句计算s=" + Str(s) End SubFor i=1 To 11 Step 2Next is=s+i1i<=11s=s+ii=i+2Loop方法1：For语句 Private Sub Command1_Click() Dim sum As Single, i As Integer sum = 0 For _____ _____ Next _____ Label2.Caption = "For语句计算sum=" + Str(sum) End Sub方法2：Do语句 Private Sub Command2_Click() Dim sum As Single, i As Integer sum = 0 _____ Do While _____ _____ _____ Loop Label2.Caption = "Do语句计算sum=" + Str(sum) End Subi=1 To 4sum=sum+i/(i+1)ii=1 i<=4 sum=sum+i/(i+1)i=i+1综合练习03Private Sub Command1_Click() Dim x As Integer, n As Integer, a As Integer, b As Integer n = 0 For x = ① a = ② 'a为十位上的数字 b = ③ 'b为个位上的数字 If ④ Then List1.AddItem Str(x) ⑤ End If Next x Label2.Caption = "共有“over”数为：" + Str(n) End Sub 有几个学生在玩报数游戏,游戏规则如下:1～99报数,首先从1开始报数,凡是报到3的倍数或数中包含数字3时,不能报出该数,要说“over”,否则将被淘汰出局。小明编写了一个报数游戏的VB程序,程序的功能为:单击“开始”按钮,将在列表框List1中输出“over”数,在标签Label3中显示“over”数的个数。程序运行效果如图所示。 ... ...