title: PHP readfile vs. file_get_contents
body: <p>I have used following code to generate zip</p>
  
  <pre><code>// push to download the zip
  header('Content-type: application/zip');
  header('Content-Disposition: attachment; filename="'.$zip_name.'"');
  readfile($zip_name);
  </code></pre>
  
  <p>this code works fine but for unknown reasons was not working until I tried</p>
  
  <pre><code>// push to download the zip
  header('Content-type: application/zip');
  header('Content-Disposition: attachment; filename="'.$zip_name.'"');
  echo file_get_contents($zip_name);
  </code></pre>
  
  <p>I am curious about finding what is happening in both the cases</p>