GoSub...Return 语句

目录

# GoSub...Return Statement

Calls a subroutine that is indicated by a label inside a Sub or a Function. The statements following the label are executed until the next Return statement. Afterwards, the program continues with the statement that follows the GoSub statement.

### 语法:

    GoSub label[:]

### 参数:

label: A line identifier indicating where to continue execution. The scope of a label in that of the routine it belongs to.

The GoSub statement calls a local subroutine indicated by a label from within a subroutine or a function. The name of the label must end with a colon (":").

      Sub/Function foo
          ' statements
          GoSub label
          ' statements
          Exit Sub/Function
      label:
          ' statements
          Return
      End Sub/Function

如果程序遇到 Return 语句之前没有「GoSub」，LibreOffice Basic 会返回一个错误信息。使用「Exit Sub」或「Exit Function」能够保证程序在到达下一个 Return 语句之前离开子程序或者函数。

以下示例用于说明「GoSub」和「Return」的使用。通过将程序段执行两遍，计算由用户输入的两个数的平方根。

### 示例:

    Sub ExampleGoSub
    Dim iInputa As Single
    Dim iInputb As Single
    Dim iInputc As Single
        iInputa = Int(InputBox("Enter the first number:","NumberInput"))
        iInputb = Int(InputBox("Enter the second number:","NumberInput"))
        iInputc=iInputa
        GoSub SquareRoot
        Print "The square root of";iInputa;" is";iInputc
        iInputc=iInputb
        GoSub SquareRoot
        Print "The square root of";iInputb;" is";iInputc
        Exit Sub
    SquareRoot:
        iInputc=sqr(iInputc)
        Return
    End Sub

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