title: Replace a tag with href link
body: <p>I have a html source code and want to replace <strong>all</strong> <code>&lt;a&gt;</code> tags with its containing href link.</p>
  
  <p>So the tag looks like:</p>
  
  <pre><code>&lt;a href="http://google.com" target="_blank"&gt;click here&lt;/a&gt;
  </code></pre>
  
  <p>I expect as output:</p>
  
  <pre><code>http://google.com
  </code></pre>
  
  <p>I already tried some regex in combination with preg_replace, 
  but none of them give me the href content.</p>
  
  <p>So what would be the best way to do this?</p>