title: preg_match(): Delimiter must not be alphanumeric or backslash
body: <p>I am trying to use preg_match to extract some data from some html. I want to get the number from the following line of an Ajax call</p>
  
  <pre><code>new Ajax.Request('/selectdata/new/get_ids?id=687420'
  </code></pre>
  
  <p>So, I have used the following PHP</p>
  
  <pre><code>preg_match('new Ajax.Request\(\'/selectdata/new/get_ids\?id=(.+?)\'', $buffer, $matches)
  </code></pre>
  
  <p>I get the message "preg_match(): Delimiter must not be alphanumeric or backslash"</p>
  
  <p>I have tried lots of variations, but no success.</p>