VBA Promming——分支语句（解二元一次方程）

分支语句

 If  expression1 Then
       expressions
 ElseIf expression2 Then
        expressions
 Else
       expression
 End If

注：VBA中等于号和赋值符号都是"=",但并不会冲突，只有在选择语句中“=”才表示是否相等

示例（交互型）

1、写好程序

2、设置动作 (View-->Toolbars-->Form Controls-->Toggle Design Mode-->Push Button)

3、绑定对应的宏 (Controls-->Events-->Mouse button pressed-->Macro-->想绑定的Macro)

代码

 Option Explicit           ‘设置变量必须先定义才能使用’
 Option VBASupport 1       ‘必须写，使得VBA能够在LibreOffice中起作用’
 Sub Main
     Dim A As Double
     Dim B As Double
     Dim C As Double
     Dim detal As Double
     A = ActiveSheet.Cells(,)
     B = ActiveSheet.Cells(,)
     C = ActiveSheet.Cells(,)
     detal = B ^  -  * A * C

     Dim x1 As Double
     Dim x2 As Double
     ActiveSheet.Cells(,) = ""
     ActiveSheet.Cells(,) = ""
     If detal >  Then
         MsgBox("two solution!")
         x1 = (-B + sqr(detal)) / ( * A)
         x2 = (-B - sqr(detal)) / ( * A)
         ActiveSheet.Cells(,) = x1
         ActiveSheet.Cells(,) = x2
     Elseif detal =   Then
         MsgBox("one solution!")
         x1 = -B / ( * A)
         x2 = x1
         ActiveSheet.Cells(,) = x1
         ActiveSheet.Cells(,) = x2
     Else
         MsgBox("no solution!")
         ActiveSheet.Cells(,) = "no solution"
         ActiveSheet.Cells(,) = "no solution"
     End if
 End Sub

 Sub clear
     ActiveSheet.Cells(,) = ""
     ActiveSheet.Cells(,) = ""
     ActiveSheet.Cells(,) = ""
     ActiveSheet.Cells(,) = ""
     ActiveSheet.Cells(,) = ""
 End sub

效果图

参考链接：https://youtu.be/TrjUbaqspNg