- var_dump: documentation ( source)
- preg_match: documentation ( source)
<?php
preg_match("!src=(\"|'|\\\\\")http://cdn.imhonet.ru/(avatars|photos|element|blog_teasers|person|file_images|video\/)(.*\/)(.)([a-z0-9\._]+)(\"|'|\\\\\")!Uis", 'http://cdn.imhonet.ru/element/large/3c/50/3c5044ee7bf3bc3a81a32f0a85607700.jpg ', $matches);
var_dump($matches);