title: is_int() cannot check $_GET in PHP?
body: <p>Here is my code:</p>
  
  <pre><code>&lt;?php
  $id = $_GET["id"];
  
  if (is_int($id) === FALSE)  {
      header('HTTP/1.1 404 Not Found');
      exit('404, page not found');
      }
  ?&gt;
  </code></pre>
  
  <p>It always enters inside the if.</p>