- var_dump: documentation ( source)
- preg_match_all: documentation ( source)
<?php
$_content = '<a href="https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p100x100/10394047_10202106066684824_80590983553430220_n.jpg?oh=fcccf17086a3593d926a100c9a82f898&oe=546AACC9&__gda__=1416199983_da92aa7319b2636ad2887652e2f9a10e">https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/p100x100/10394047_10202106066684824_80590983553430220_n.jpg?oh=fcccf17086a3593d926a100c9a82f898&oe=546AACC9&__gda__=1416199983_da92aa7319b2636ad2887652e2f9a10e</a>';
if(preg_match_all('#<a href=\"https://fbcdn([^\?\'"]*?)(.jpg|.gif|.png)\?([^\'"]*?)[^>]*>([^<]*?)</a>#i', $_content, $matches));
var_dump($matches);