'Eine Progressbar für Prozentzählung auf die Form setzen
  Dim probar As New ProgressBar With _
     {.Parent = Me, .Minimum = 1, .Maximum = 100}
 
 
  Private Sub SplitFile()
 
     Dim basefile As String = "C:\daten\split.txt" 'zu splittendes File
 
     Dim totallength As Long = New IO.FileInfo(basefile).Length 'Gesamtlänge
 
     Dim readlength As Long = 0
     Dim linecount As Long = 0, percent As Integer = 0
 
     Dim lines As New List(Of String), line As String = ""
     Dim outpath As String = "C:\daten", outfile As String = ""
 
     Using sr As New IO.StreamReader(basefile)
        While Not sr.EndOfStream
           line = sr.ReadLine
           lines.Add(line)
 
           readlength += line.Length + 2 'CRLF
           linecount += 1
           If linecount Mod 100 = 0 Then
              'Progressbar aktualisieren
              percent = CInt(readlength * 100 / totallength)
              probar.Value = percent
              probar.Refresh()
           End If
 
           If line.StartsWith("PG_Bezeichnung".ToUpper) Then
              Dim filename As String = _
                 line.Substring(line.IndexOf("=") + 1) & ".txt"
              outfile = IO.Path.Combine(outpath, filename)
           End If
 
           If Not outfile = "" Then
              If line.StartsWith("[Hauptprogramm]".ToUpper) Then
                 lines.RemoveAt(lines.Count - 1)
                 IO.File.WriteAllLines(outfile, lines)
                 lines.Clear()
                 lines.Add(line)
                 outfile = ""
              End If
           End If
        End While
     End Using
 
     If Not lines.Count = 0 And Not outfile = "" Then
        IO.File.WriteAllLines(outfile, lines)
     End If
  End Sub