private sub 可以将新创建的变量传递给 main() 吗？

Question

私有子程序是否可以在从主程序接收到值后与主程序在同一模块中，创建新变量并将其传回主程序？

这就是我想要做的，但我遇到了一些困难。例如，在下面的 testSUB 中，我更改了字符串。我可以将 extraSTRING 和 newSTRING 传递回 main 吗？任何示例都会有所帮助。

Module module1
    Sub main()
        Dim l As String
        Dim I As Long = 1
        Dim A As String
        testsub(l, A, I)
    End Sub

    Private Sub testSub(l As String, A As String, I As Long)
        Dim extraSTRING As String = "extraTEXT"
        Dim newSTRING As String = l & extraSTRING
    End Sub
End Module

Answer 1

到 return 一个值你可以把你的 Sub 变成 Function:

Private Function testFunction (ByVal arg1 As String) As String

    Return arg1 & " and some more text"

End Function

要调用上面的 Function 并分配值 returned 使用此代码：

Dim a As String = testFunction("some text")

'Output:
'a = "some text and some more text"

下面是带有输出的代码的屏幕截图：

或者您可以使用 ByRef:

Specifies that an argument is passed in such a way that the called procedure can change the value of a variable underlying the argument in the calling code.

ByRef 与 ByVal 略有不同：

Specifies that an argument is passed in such a way that the called procedure or property cannot change the value of a variable underlying the argument in the calling code.

下面是一些示例代码，向您展示了操作上的差异：

Module Module1

    Sub Main()
        Dim a As Integer = 0
        Dim b As Integer = 0
        Dim c As Integer = 0

        testSub(a, b, c)

        'Output:
        'a = 0
        'b = 0
        'c = 3

    End Sub

    Private Sub testSub(arg1 As Integer, ByVal arg2 As Integer, ByRef arg3 As Integer)
        arg1 = 1
        arg2 = 2
        arg3 = 3
    End Sub

End Module

通过不在 VB.NET 中指定 modifier（如上面 arg1 所示）编译器默认情况下将使用 ByVal.

It would be good to note here that although VB.NET uses ByVal by default if not specified, VBA does not and instead by default uses ByRef. Beware of this should you ever port code from one to the other.

下面是带有输出的代码的屏幕截图：

以您的代码为例：

Sub main()
    Dim l As String
    Dim A As String
    Dim I As Long = 1
    testSub(l, A, I)
End Sub

要传递变量 l、A 和 I 并更改它们的值，您需要更改方法以使用修饰符 ByRef.

Private Sub testSub(ByRef l As String, ByRef A As String, ByRef I As Long)
    l = "TEXT"
    A = "extra" & l
    I = 100
End Sub

下面是带有输出的代码的屏幕截图：

private sub 可以将新创建的变量传递给 main() 吗？

Can private sub pass newly created variable to main()?

vb.net

string

main

module

parameter-passing

private sub 可以将新创建​​的变量传递给 main() 吗？

Can private sub pass newly created variable to main()?

vb.net

string

main

module

parameter-passing

private sub 可以将新创建的变量传递给 main() 吗？