title: fastest way to determine if array has a length?
body: <p>If I am creating an array from some results from an sql query like so:</p>
  
  <pre><code>$res[] = self::create_array($q2-&gt;row_array());
  </code></pre>
  
  <p>wouldn't it be faster to do <code>if (isset($res[0]))</code> rather than <code>if (count($res) &gt; 0)</code>? The size of some of the results arrays are around 1500 elements; or is the optimization in this area negligible?</p>