title: Empty variable define in php
body: <p>Before doing something with <strong>$error</strong>:</p>
  
  <pre><code>$error = NULL;
  </code></pre>
  
  <p>In some script's saw:</p>
  
  <pre><code>$error = '';
  $error = false;
  $error = 0;
  </code></pre>
  
  <ul>
  <li>Which method is 'better' or maybe it depends in which situation i use
  it ?</li>
  <li>What's your suggestion ?</li>
  </ul>