Private Sub cmd_abgleich_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmd_abgleich.Click
        Dim fname_er As String
        Dim fname_belegnr As String
        Dim line_er As String = ""
        Dim line_belegnr As String = ""
        Dim belegnr_er As String = ""
        Dim belegnr_belegnr As String = ""
        Dim tmp_er As ArrayList = New ArrayList
        Dim tmp_bn As ArrayList = New ArrayList
 
        fname_er = txt_er.Text
        fname_belegnr = txt_belegnr.Text
 
        Dim fs_er As FileStream = New FileStream(fname_er, _
          FileMode.OpenOrCreate, FileAccess.ReadWrite)
        Dim fs_bn As FileStream = New FileStream(fname_belegnr, _
        FileMode.OpenOrCreate, FileAccess.ReadWrite)
        Dim sr_er As StreamReader = New StreamReader(fs_er)
        Dim sr_bn As StreamReader = New StreamReader(fs_bn)
        Dim sw_er As StreamWriter = New StreamWriter(fs_er)
 
        If MsgBox("WARNUNG ! Es werden nun nicht mehr benötigte Daten aus dem" & _
          "ER File entfernt !" & vbCrLf & "Falls Sie noch kein Backup der" & _
          "Originaldatei angelegt haben, so tun Sie dies bitte jetzt.", _
          MsgBoxStyle.Critical + MsgBoxStyle.OkCancel) = MsgBoxResult.Cancel _
          Then GoTo abort Else 
 
        Dim x As Decimal = 0
        Do While Me.Opacity > 0.5
            Me.Refresh()
            Me.Opacity -= 0.05
            For x = 1 To 100000
            Next x
        Loop
 
 
        Do Until sr_bn.Peek = -1
            If sr_bn.Peek = -1 Then Exit Sub
            line_belegnr = sr_bn.ReadLine()
            belegnr_belegnr = line_belegnr.Substring(0, 7)
            tmp_bn.Add(belegnr_belegnr)
            'If belegnr_er <> belegnr_belegnr Then
            'sw_er.WriteLine(tmp_er)
            'sw_er.BaseStream.SetLength(sw_er.BaseStream.Length - LineLength)
            'Else
            'End If
        Loop
 
        Do Until sr_er.Peek = -1
            If sr_er.Peek = -1 Then Exit Sub
            line_er = sr_er.ReadLine
            belegnr_er = line_er.Substring(11, 7)
            If belegnr_er = tmp_bn.Contains(belegnr_er) Then
            Else
                sw_er.WriteLine()
            End If
        Loop
 
        Do While Me.Opacity < 1.0
            Me.Refresh()
            Me.Opacity += 1.0
            For x = 1 To 100000
            Next x
        Loop
 
 
abort:
    End Sub