title: How to replace a special xml tag by using php
body: <p>I have a xml file such as this:    </p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;datas&gt;
  &lt;books&gt; 
  &lt;book&gt;
  &lt;id&gt;1&lt;/id&gt;
  &lt;title&gt;PHP Undercover&lt;/title&gt;     
  &lt;author&gt;Wiwit Siswoutomo&lt;/author&gt;
  &lt;/book&gt;`enter code here`
  &lt;book&gt;
  &lt;id&gt;2&lt;/id&gt;
  &lt;title&gt;PHP Enterprise&lt;/title&gt;     
  &lt;author&gt;Wiwit Siswoutomo&lt;/author&gt;
  &lt;/book&gt;
  &lt;/books&gt;
  &lt;/datas&gt;
  </code></pre>
  
  <p>and now i wana to replace a special tag in this way:
  search in xml file and if it has a PHP Enterprise ,find it and replace it by 'new title'.
  What should i do?
  TNX</p>