vb.net验证包含后退的字符串

Question

说我有以下字符串：

C:\folder1\folder2\ <- this is valid
C:\foler1\folder2 <- this is invalid
C:\folder1\folder2\folder3 <- invalid

基本上我想检查用户输入的目录是否为

格式

C:\somthing\somthing\

其他任何内容无效

最佳方法？正则表达式？或字符串函数？

当前的vb方法：

Private Sub txtboxLocRoot_Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs)   Handles txtboxLocRoot.Validating

    If txtboxLocRoot.Text.Split("\").Length - 1 <> 3 Then
        MsgBox("Local root must be in the format 'C:\dir1\[folder name]\'", vbExclamation, "Error")
        Return
    End If

    Dim foldernamearray() As String = Split(txtboxLocRoot.Text, "\")
    pfoldername = foldernamearray(2)
    txtboxLocRoot.Text = "C:\dir1\" & pfoldername & "\"

End Sub

Answer 1

要启动并运行一些快速而脏的字符串函数，为什么不能这样：

If value.StartsWith("c:\") and value.EndsWith("\") then
    'it's starting to look OK
    'do some further testing for a single "\" in the middle section
End If

然后还使用Path.GetInvalidFileNameChars和Path.GetInvalidPathChars检查那里没有垃圾。

Answer 2

也许不优雅，但更好的错误检查：

的修订版 的

Private Sub Test()

    Dim [Directory] As String = "C:\dir1\dir2\"

    If DirectoryValidator([Directory]) Then
        ' Continue...
    Else
        ' Throw
    End If

End Sub

''' <summary>
''' Validates a directory path.
''' </summary>
''' <param name="Directory">
''' Indicates the directory to validate.
''' </param>
''' <returns><c>true</c> if validated successfully, <c>false</c> otherwise.</returns>
''' <exception cref="Exception">
''' Too less directories.
''' or
''' Too much directories.
''' or
''' Bad syntax.
''' or
''' Missing '\' character.
''' </exception>
Private Function DirectoryValidator(ByVal [Directory] As String) As Boolean

    Select Case [Directory].Contains("\")

        Case True
            If [Directory].StartsWith("C:\", StringComparison.OrdinalIgnoreCase) AndAlso [Directory].EndsWith("\") Then

                Dim PartsLength As Integer = [Directory].Split({"\"}, StringSplitOptions.RemoveEmptyEntries).Length
                Dim InvalidChars As Char() = IO.Path.GetInvalidPathChars

                If PartsLength < 3 Then
                    Throw New Exception("Too less directories.")
                    Return False

                ElseIf PartsLength > 3 Then
                    Throw New Exception("Too much directories.")
                    Return False

                ElseIf (From c As Char In [Directory] Where InvalidChars.Contains(c)).Any Then
                    Throw New Exception("Invalid characters.")
                    Return False

                End If

            Else
                Throw New Exception("Bad syntax.")
                Return False

            End If

        Case Else
            Throw New Exception("Missing '\' character.")
            Return False

    End Select

    Return True

End Function