vb.net - 我们可以在函数 vb.net 中返回两个变量值吗？

Question

我们可以在函数 vb.net 中返回两个值吗

Public Function jaggedarr(ByRef arr()() As Integer, ByVal keyvalue As Integer) As String

    For i As Integer = 0 To arr.GetUpperBound(0)
        For j As Integer = 0 To arr(i).GetUpperBound(0)
            If arr(i)(j) = keyvalue Then
                Return i j
            End If
        Next
    Next

End Function`

Answer 1

我可以为您提供三种方法。

首先是使用Tuple(Of Integer, Integer)。

Public Function jaggedarr(ByRef arr()() As Integer, ByVal keyvalue As Integer) As Tuple(Of Integer, Integer)
    For i As Integer = 0 To arr.GetUpperBound(0)
        For j As Integer = 0 To arr(i).GetUpperBound(0)
            If arr(i)(j) = keyvalue Then
                Return Tuple.Create(i, j)
            End If
        Next
    Next
End Function

第二个是定义您自己的返回类。

Public Function jaggedarr(ByRef arr()() As Integer, ByVal keyvalue As Integer) As Pair
    For i As Integer = 0 To arr.GetUpperBound(0)
        For j As Integer = 0 To arr(i).GetUpperBound(0)
            If arr(i)(j) = keyvalue Then
                Return New Pair(i, j)
            End If
        Next
    Next
End Function

Public NotInheritable Class Pair
    Implements IEquatable(Of Pair)

    Private ReadOnly _I As Integer

    Private ReadOnly _J As Integer

    Public ReadOnly Property I As Integer
        Get
            Return _I
        End Get
    End Property

    Public ReadOnly Property J As Integer
        Get
            Return _J
        End Get
    End Property

    Public Sub New(I As Integer, J As Integer)
        _I = I
        _J = J
    End Sub

    Public Overrides Function Equals(obj As Object) As Boolean
        If TypeOf obj Is Pair
            Return Equals(DirectCast(obj, Pair))
        End If

        Return False
    End Function

    Public Overloads Function Equals(obj As Pair) As Boolean Implements IEquatable(Of Pair).Equals
        If obj Is Nothing
            Return False
        End If

        If Not EqualityComparer(Of Integer).[Default].Equals(_I, obj._I)
            Return False
        End If

        If Not EqualityComparer(Of Integer).[Default].Equals(_J, obj._J)
            Return False
        End If

        Return True
    End Function

    Public Overrides Function GetHashCode() As Integer
        Dim hash As Integer = 0
        hash = hash Xor EqualityComparer(Of Integer).[Default].GetHashCode(_I)
        hash = hash Xor EqualityComparer(Of Integer).[Default].GetHashCode(_J)
        Return hash
    End Function

    Public Overrides Function ToString() As String
        Return [String].Format("{{ I = {0}, J = {1} }}", _I, _J)
    End Function
End Class

第三种，可能也是最有趣的方法是传递返回委托(delegate)。

Public Sub jaggedarr(ByRef arr()() As Integer, ByVal keyvalue As Integer, ByVal [return] As Action(Of Integer, Integer))
    For i As Integer = 0 To arr.GetUpperBound(0)
        For j As Integer = 0 To arr(i).GetUpperBound(0)
            If arr(i)(j) = keyvalue Then
                [return](i, j)
            End If
        Next
    Next
End Sub

此方法从 Function 更改为 Sub，并且 [return] As Action(Of Integer, Integer) 允许多个返回值多对。

您甚至可以将其与 Pair 类结合起来并执行以下操作:

Public Sub jaggedarr(ByRef arr()() As Integer, ByVal keyvalue As Integer, ByVal [return] As Action(Of Pair))
    For i As Integer = 0 To arr.GetUpperBound(0)
        For j As Integer = 0 To arr(i).GetUpperBound(0)
            If arr(i)(j) = keyvalue Then
                [return](New Pair(i, j))
            End If
        Next
    Next
End Sub