3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php $input = array( array( 'tag_name' => array('google', 'Yahoo') ), array( 'tag_name' => array('technology', 'andsuch') ) ); echo implode(', ', array_walk(function ($entry) { return $entry['tag_name']; }, $input));
Output for 5.3.0 - 5.4.29
Fatal error: Only variables can be passed by reference in /in/HGVLp on line 13
Process exited with code 255.