title: CodeIgniter Controller Constructor
body: <p>I'm very new to codeigniter , 
  I wanted to know what is the meaning of a constructor in a controller . I saw the following code in a codeigniter tutorial - </p>
  
  <pre><code>class upload extends CI_Controller {
  
      function __construct() {
          parent::__construct();
          $this-&gt;load-&gt;helper(form);
      }
  
      // rest of the class...
  </code></pre>
  
  <p>My question is when is the constructor invoked - is it called every time the controller serves a request (e.g the controller class is instantiated for each request it receives?)</p>