fs.Seek(0, IO.SeekOrigin.End)

      Sub buchdateifuellen(ByVal buchnr As String, ByVal titel As String, ByVal _
        autor As String)
            Dim dateiname As String = "buecher.dat"
            Dim fs As New IO.FileStream(dateiname, IO.FileMode.OpenOrCreate)
            Dim bw As New IO.BinaryWriter(fs)
            fs.Seek(0, IO.SeekOrigin.End)
            bw.Write(buchnr)
            bw.Write(titel)
            bw.Write(autor)
            bw.Close()