3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php echo preg_replace('/\\\(?!.*\\\)$/', '\Trig\\1', 'asd\qwer\thgsd\Boom');
based on kaDhX
Output for 4.3.0 - 7.1.0
asd\qwer\thgsd\Boom