3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php var_dump(preg_match('/(?<=\b)рус(?:\b)/uis', 'рус'));
Output for 5.3.4 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
int(1)
Output for 4.3.0 - 5.3.3
int(0)