Const Datei = "d:\testverzeichnis\testdatei.txt"
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim iZahl As Integer = GetNextNumber()
 
        MessageBox.Show(iZahl)
 
 
    End Sub
 
 
    Private Function GetNextNumber() As Integer
        Dim sr As New System.IO.StreamReader(Datei)
        Dim iZeile As String = CInt(sr.ReadLine.Trim) + 1
        sr.Close()
 
        Dim sw As New System.IO.StreamWriter(Datei)
        sw.WriteLine(iZeile)
        sw.Close()
 
        Return iZeile
 
    End Function

EALA FREYA FRESENA