title: CodeIgniter - Private functions
body: <p>I have started playing with CodeIgniter now.
  And I use their user guide and other third-party tutorials available for learning. I'm a bit stuck at the naming of private functions. Based on <a href="http://ellislab.com/codeigniter/user_guide/general/controllers.html#private" rel="nofollow">the user guide</a>, I have to prefix a <code>_</code> in the name of private functions. But <a href="http://www.jotorres.com/2012/03/create-user-login-with-codeigniter/" rel="nofollow">in this tutorial</a>, check the <strong>Add Logout</strong> section. In it, there is a private function: <code>private function check_isvalidated()</code>. Here, it is not prefixed with the character <code>_</code>.</p>
  
  <p>So that's also an accepted naming convention ?
  At the same time, there is another one called <code>_output()</code>: <a href="http://ellislab.com/codeigniter/user_guide/general/controllers.html#output" rel="nofollow">Processing Output</a>.
  It's a public function with the naming convention of a private function !</p>
  
  <p>It's a bit of confusing when I try to learn in a systematic manner.</p>