Online PHP editor | refs for GAKXf

<?php $params = array('username' => "l33t"); $route = "/user/[a-z0-9:username]"; echo preg_replace_callback('~\[([a-z0-9\.\-_\+]+)\:([a-z0-9\_]+)\]~', function($matches) use(&$params) { if(isset($params[$matches[2]])){ return $params[$matches[2]]; }else{ return 'null'; } }, $route);