The PHP implementation intercepts the primary domain name in a URL

PHP example tutorial, how to intercept a URL in the main domain name, the following code:
<?php
$S = ' http://bbs.webjx.com ';
$S = Parse_url ($S);
$S = Strtolower ($S [' Host ']); Take the domain name part
Echo $S;

$domain = Array (' com ', ' cn ', ' name ', ' org ', ' net '); The domain suffix has a new extension.
$SS = $S;
$DD = Implode (", $domain);
$SS = Preg_replace ('/(\. $dd. ') *\. (' $dd. ') $/iu ', ', $SS); Remove the suffix part of the following domain

$SS = Explode ('. ', $SS);
$SS = Array_pop ($SS); Take the last primary domain name
$SS = substr ($S, Strrpos ($S, $SS)); Add suffix to the completed primary domain
Echo $SS;
?>