3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php //$p = '~(?J)(z?)((?1)(?P<group>b)|(?P<group>a))ba~'; // works $p = '~(?J)(z?)((?1)(?P<group>b)|(?P<group>a))b(?P=group)~'; // fails $s = 'aba'; if (preg_match($p, $s, $m)) { var_dump($m); }
Output for 5.4.41 - 5.6.28, hhvm-3.12.0, 7.0.0 - 7.1.0
array(6) { [0]=> string(3) "aba" [1]=> string(0) "" [2]=> string(1) "a" ["group"]=> string(1) "a" [3]=> string(0) "" [4]=> string(1) "a" }
Output for hhvm-3.10.0

Process exited with code 153.
Output for 4.4.5 - 4.4.9, 5.2.0 - 5.4.40
Output for 4.3.11 - 4.4.4, 5.0.0 - 5.1.6
Warning: preg_match(): Compilation failed: unrecognized character after (? at offset 2 in /in/h5NbX on line 8
Output for 4.3.0 - 4.3.10
Warning: Compilation failed: unrecognized character after (? at offset 2 in /in/h5NbX on line 8