Understanding class required and exist
<p>I download a framework and code and I have a question regarding <code>require</code> and <code>include</code> vs <code>class_exists</code>.</p>

<p>In the code I download, I see:</p>

<pre><code>require_once('class.php');
</code></pre>

<p>As well as:</p>

<pre><code>if(class_exists('class') == false) {  require('class.php'); }
</code></pre>

<p>I get <code>require_once</code> means only 1 time and class exists check if the class exists.</p>

<p>My question is: is the second better than the first one? and why?</p>
