title: Extract domain from url (including the hard ones)
body: <p>I'm trying to write (or just find an existing) PHP method that can take a link and extract the url. The trick is, it needs to hold under the weight of strange looking domains like:</p>
  
  <pre><code>www.champa.kku.ac.th 
  </code></pre>
  
  <p>Looking at this one myself with human eyes, I still guessed it incorrectly: thought the domain would be <code>kku.ac.th</code> but that gives a dns error when visiting. </p>
  
  <p>So anyone knows of a good way to reliably extract the domain from url: </p>
  
  <pre><code>http://site.com/hello.php
  http://site.com.uk/hello.php
  http://subdomain.site.com/hello.php
  http://subdomain.site.com.uk/hello.php
  http://www.champa.kku.ac.th/hello.php // and even the one I couldn't tell
  </code></pre>