ExcelVBA之If then

在VBA过程里面作决定的最简单的方法就是使用If…Then语句。假使你想要基于某个条件选择一个行动，那么你可以使用下述结构：

 If 条件Then
    语句1
    语句2
    语句N
End If

如何使用On Error GoTo标志语句来绕过循环错误:

Sub SimpleIfThen()
    Dim weeks As String
    On Error GoTo VeryEnd
    weeks = InputBox("How many weeks are in a year:", "Quiz")
    If weeks<>52 Then MsgBox "Try Again": SimpleIfThen
    If weeks=52 Then MsgBox "Congratulations!"
    VeryEnd:
End Sub

 过程IfThenAnd使用了四个If…Then语句来评估两个变量price和units的内容。在If…Then关键字之间的运算符AND使得测试多于一个的条件成为可能。使用了AND运算符时，所有条件都必须为真，VB才会去执行关键字Then和End之间的语句。因为过程的运行依赖于工作表单元格里输入的数据，所以从Excel窗口来运行它比较方便。

Sub IfThenAnd()
    Dim price As Single
    Dim units As Integer
    Dim rebate As Single
    Const strmsg1 = "To get a rebate you must buy an additional "
    Const strmsg2 = "Price must equal $7.00"
    units = Range("B1").Value
    price = Range("B2").Value
    If price = 7 AND units >= 50 Then
        rebate = (price * units) * 0.1
        Range("A4").Value = "The rebate is: $" & rebate
    End If
    If price = 7 AND units < 50 Then
        Range("A4").Value = strmsg1 & 50 - units & " unit(s)."
    End If
    If price <> 7 AND units >= 50 Then
        Range("A4").Value = strmsg2
    End If
    If price <> 7 AND units < 50 Then
        Range("A4").Value = "You didn't meet the criteria."
    End If
End Sub

总结：指令块和缩进，要使If程序块更容易阅读和理解，可以使用缩进。对比下面的代码书写：

If condition Then
action1
End If
If condition Then
   action
End If