title: Limit lines of a txt file
body: <p>I have a text file where I save a line every 30 minutes with the WriteLineAsync method. When the file become too large, if I try to read it, the application crashes. I thought that I could limit the lines writable on the file so when I add a new line, the oldest line will be deleted.
  How can I do that?</p>
  
  <p>edit:
  I read the file with the following code:</p>
  
  <pre><code>StorageFile MyFile = await ApplicationData.Current.LocalFolder.GetFileAsync("LogFile.txt");
  string nextLine;
  using (StreamReader reader = new StreamReader(await MyFile.OpenStreamForReadAsync()))
  {
      while ((nextLine = await reader.ReadLineAsync()) != null)
      {
          TextLog.Text += nextLine + "\n";
      }
  }
  </code></pre>
  
  <p>I've tried to debug it and I don't get any exception from the reading code. Maybe the problem is that I try to put all that text in a textblock.</p>