whats wrong with this code in php
<p>I'm getting this message when I try to run a php script</p>

<blockquote>
  <p>Warning: preg_replace() [function.preg-replace]: Unknown modifier '.'</p>
</blockquote>

<p>This is the code:</p>

<pre><code>$ext = preg_replace("^.+\\.([^.]+)$", "\\1", $file);
</code></pre>
