Can anyone explain this warning?
<p>What is the meaning of of the warning? </p>

<pre><code>Warning: preg_replace() [function.preg-replace]: Compilation failed: PCRE does not support \L, \l, \N{name}, \U, or \u at offset 1 in
</code></pre>

<p>It's being triggered by this function:</p>

<pre><code>file_put_contents($file,preg_replace('(\uid=\d+)', 'uid=' . $uid, file_get_contents($file)));
</code></pre>

<p>Namely this pattern:</p>

<pre><code>'(\uid=\d+)'
</code></pre>

<p>It works locally, but not online, meaning it's probably my host's version of PHP. I've tried to google a work-around, but can't find anything.</p>
