Private Function Klammerpaarung(txt As String, pos As Integer) As Integer
 
        Dim öffnend As String = "([{"
        Dim schließend As String = ")]}"
 
        If pos < 0 Or pos > txt.Length - 2 Then Return -1
 
        Dim co As Char = txt(pos)
        Dim ind As Integer = öffnend.IndexOf(co)
        If ind = -1 Then Return -1
        Dim cc As Char = schließend(ind)
 
        Dim cnt As Integer = 1
 
        Do
            pos += 1
            If txt(pos) = co Then cnt += 1 'öffnend
            If txt(pos) = cc Then  'schließend
                cnt -= 1
                If cnt = 0 Then Return pos
            End If
        Loop While pos < txt.Length - 1
        Return -1
    End Function

        Dim txt As String = "(aa{bb{cc{dd{ee}ff}gg}hh}ii)"
 
        Dim pos As Integer = Klammerpaarung(txt, 6)