正则表达式从RSS文件中删除标签和内容

Question

This is the example structure of my RSS file:

<item>
 <title>My Title</title>
 <link>http://www.link.com</link>
 <description>The description</description>
 <author>Blah Blah</author>
 <pubDate>Thu, 26 Jul 2012 10:17:15 -0400</pubDate>
 <media:content url="myimage.jpg">
  <media:title>sdafsd</media:title>
 </media:content>
 <position>1</position>
</item>

How can I remove the author tag and its contents, the entire media:content tag and its contents, and the position tag and its contents completely from the file using PHP regular expressions?

Thanks!

Answer 1

My previous answer was - rightfully - removed, I should have added it as a comment. Here's an alternative with DomDocument doing exactly what you want to do:

<?php

$xml = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
  <channel>
    <title>bla</title>
    <link>bla</link>
    <description>A description</description>
    <language>en-us</language>
    <item xmlns:media="http://search.yahoo.com/mrss/">
     <title>My Title</title>
     <link>http://www.link.com</link>
     <description>The description</description>
     <author>Blah Blah</author>
     <pubDate>Thu, 26 Jul 2012 10:17:15 -0400</pubDate>
     <media:content url="myimage.jpg">
      <media:title>sdafsd</media:title>
     </media:content>
     <position>1</position>
    </item>
  </channel>
</rss>
XML;

$doc = new DOMDocument();
$doc->loadXml( $xml );

foreach( $doc->getElementsByTagName( 'item' ) as $item ) {
    $item->removeChild( $item->getElementsByTagName( 'author' )->item( 0 ) );
    $item->removeChild( $item->getElementsByTagName( 'position' )->item( 0 ) );
            $item->removeChild( $item->getElementsByTagName( 'content' )->item( 0 ) );
}

var_dump( $doc->saveXml( ) );