vb.net可变参数与参数省略

可变参数

ParamArray 修饰符使函数能够接受可变数量的参数。

Public Function calcSum(ByVal ParamArray args() As Double) As Double
    calcSum = 0
    If args.Length <= 0 Then Exit Function
    For i As Integer = 0 To UBound(args, 1)
        calcSum += args(i)
    Next i
End Function

 

Optional

指定在调用过程时可以省略过程参数。

必须为所有可选过程参数指定默认值。

 

Public Function FindMatches(ByRef values As List(Of String),
                            ByVal searchString As String,
                            Optional ByVal matchCase As Boolean = False) As List(Of String)

    Dim results As IEnumerable(Of String)

    If matchCase Then
        results = From v In values
                  Where v.Contains(searchString)
    Else
        results = From v In values
                  Where UCase(v).Contains(UCase(searchString))
    End If

    Return results.ToList()
End Function