Question

I am trying to copy a text file in an other text file line by line. It seems that there is a buffer of 1024 character. If there is less than 1024 character in my file, my function will not copie in the other file.

Also if there is more than 1024 character but less a factor of 1024, these exceeding characters will not be copied.

Ex:

2048 character in initial file – 2048 copied

988 character in initial file – 0 copied

1256 character in initial file – 1024 copied

private void button3_Click(object sender, EventArgs e)
{
    // écrire code pour reprendre le nom  du fichier sélectionné et 
    //ajouter un suffix "_poly.txt"
    string ma_ligne;
    const int RMV_CARCT = 9;

    //délcaration des fichier
    FileStream apt_file = new FileStream(textBox1.Text, FileMode.Open, FileAccess.Read);
    textBox1.Text = textBox1.Text.Replace(".txt", "_mod.txt");
    FileStream mdi_file = new FileStream(textBox1.Text, FileMode.OpenOrCreate,FileAccess.ReadWrite);

    //lecture/ecriture des fichiers en question
  StreamReader apt = new StreamReader(apt_file);
  StreamWriter mdi_line = new StreamWriter(mdi_file, System.Text.Encoding.UTF8, 16);



  while (apt.Peek() >= 0)
  {
      ma_ligne = apt.ReadLine();
      //if (ma_ligne.StartsWith("GOTO"))
      //{
      //   ma_ligne = ma_ligne.Remove(0, RMV_CARCT);
      //   ma_ligne = ma_ligne.Replace(" ","");
      //   ma_ligne = ma_ligne.Replace(",", " ");
      mdi_line.WriteLine(ma_ligne);
      //}
  }
  apt_file.Close();
  mdi_file.Close();
}

Answer 1

Two issues:

1. Your FileStream, StreamWriter, and StreamReader classes should be inside using { } blocks. They implement IDisposable, so you need to be calling Dispose, and the using block will do that for you. If you do this, that’s actually all you have to fix (which I’ll explain in a minute). Doing this also means you no longer need to call Close().
2. At a minimum, call mdi_line.Flush() before closing it. This will cause the buffer to be written to the file immediately.

Calling Dispose on the StreamWriter class autmatically calls Flush, which is why the using block will correct the problem.

using (FileStream apt_file = new FileStream(textBox1.Text, FileMode.Open, FileAccess.Read))
{
    textBox1.Text = textBox1.Text.Replace(".txt", "_mod.txt");

    using (FileStream mdi_file = new FileStream(textBox1.Text, FileMode.OpenOrCreate, FileAccess.ReadWrite))
    {
        //lecture/ecriture des fichiers en question 
        using (StreamReader apt = new StreamReader(apt_file))
        using (StreamWriter mdi_line = new StreamWriter(mdi_file, System.Text.Encoding.UTF8, 16))
        {
            while (apt.Peek() >= 0)
            {
                ma_ligne = apt.ReadLine();
                //if (ma_ligne.StartsWith("GOTO")) 
                //{ 
                //   ma_ligne = ma_ligne.Remove(0, RMV_CARCT); 
                //   ma_ligne = ma_ligne.Replace(" ",""); 
                //   ma_ligne = ma_ligne.Replace(",", " "); 
                mdi_line.WriteLine(ma_ligne);
                //} 
            }
        }
    }
}