vb.net - mci 状态位置/长度失败

Question

我试图检查声音文件是否已在 vb.net 中使用 windows MCI API 结束，但它不断出现无效的设备名称（263 - MCIERR_INVALID_DEVICE_NAME），是因为我的语法还是其他错误？

  Public Sub CheckAndPlay(ButtonName As String)
        Dim Target As Integer
        Dim Position As String = Space(256)
        Dim Length As String = Space(256)

        Target = Microsoft.VisualBasic.Right(ButtonName, 2)

        w = mciSendString("status " & Target & " position", Position, 256, 0)
        w = mciSendString("status " & Target & " length", Length, 256, 0)

        If Val(Position) = Val(Length) - 10 Or Val(Length) = Nothing Or Val(Position) = 0 Or Val(Position) = Nothing Then
            w = mciSendString("play " & ButtonName, Nothing, 0, 0)
        End If
    End Sub

Answer 1

为什么 Target 定义为整数，然后添加为空字符串？Microsoft.VisualBasic.Right(ButtonName, 2) 实际上是否返回一个定义为整数的字符串？也许将 Target 重新定义为字符串，然后在将其传递给 mciSendString 之前检查以确保它不是空字符串。