vb.net - 是否可以在 VB.NET 中使用带有可为空值的 Select Case？

Question

以下代码

Sub Foo(i As Int32?)
    Select Case i
        Case Nothing              ' <-- warning here
            ' Do something
        Case 0
            ' Do something else
        Case Else
            ' Do something different
    End Select
End Sub

产生以下警告:

Warning BC42037: This expression will always evaluate to Nothing (due to null propagation from the equals operator). To check if the value is null consider using 'Is Nothing'.

但是，

Case Is Nothing 会产生语法错误:

Error BC30239: Relational operator expected.

有没有办法将 Select Case 与可为空值类型和 Nothing 情况的 case 子句结合使用？

Answer 1

这是我目前使用的解决方法。我期待其他在多个 Case 子句的情况下减少重复的解决方案:

Select Case True
    Case i Is Nothing
        ' Do something
    Case i = 0
        ' Do something else
    Case Else
        ' Do something different
End Select