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# If...Then...Else Statement

Defines one or more statement blocks that you only want to execute if a given condition or expression is True.

### Syntax:

      If condition Then
          statements
      [{ElseIf|Else If} expression Then
          statements]
      [Else
          statements]
      {EndIf|End If}

Instead of Else If you can write ElseIf, instead of End If you can write EndIf.

If statements can be shortened to one line when using single statement blocks.

      If condition Then statement [Else statement]

### Parameters:

The If...Then statement executes program blocks depending on given conditions. When LibreOffice Basic encounters an If statement, the condition is tested. If the condition is True, all subsequent statements up to the next Else or ElseIf statement are executed. If the condition is False, and an ElseIf statement follows, LibreOffice Basic tests the next expression and executes the following statements if the condition is True. If False, the program continues either with the next ElseIf or Else statement. Statements following Else are executed only if none of the previously tested conditions were True. After all conditions are evaluated, and the corresponding statements executed, the program continues with the statement following EndIf.

If...Then 陳述式可以多層嵌套。

Else 和 ElseIf 陳述式是可選擇的。

您可以使用 GoTo 和 GoSub 跳出 If...Then 區塊，但是不能跳入 If...Then 結構。

### Example:

以下示例可讓您輸入產品的有效期並確定產品是否已過期。

    Sub ExampleIfThenDate
        Dim sDate As String
        Dim sToday As String
        sDate = InputBox("Enter the expiration date (MM.DD.YYYY)")
        sDate = Right$(sDate, 4) + Mid$(sDate, 4, 2) + Left$(sDate, 2)
        sToday = Date$
        sToday = Right$(sToday, 4)+ Mid$(sToday, 4, 2) + Left$(sToday, 2)
        If sDate < sToday Then
            MsgBox "The expiration date has passed"
        ElseIf sDate > sToday Then
            MsgBox "The expiration date has not yet passed"
        Else
            MsgBox "The expiration date is today"
        End If
    End Sub

相關主題

Select Case statement

Iif or Switch functions