3v4l.org

run code in 150+ php & hhvm versions
Bugs & Features
<?php preg_match('/(?>[A-Za-z])+(?[A-Za-z])+/', 'FooBar', $m); var_dump($m); preg_match('/([A-Za-z])++([A-Za-z])+/', 'FooBar', $m); var_dump($m);
based on eqKvQ
Output for 5.2.6 - 7.1.0
Warning: preg_match(): Compilation failed: unrecognized character after (? or (?- at offset 15 in /in/b5Pi9 on line 3 NULL array(0) { }
Output for 5.2.0 - 5.2.5
Warning: preg_match(): Compilation failed: unrecognized character after (? at offset 15 in /in/b5Pi9 on line 3 NULL array(0) { }
Output for 4.3.11 - 4.4.8, 5.0.0 - 5.1.6
Warning: preg_match(): Compilation failed: unrecognized character after (? at offset 15 in /in/b5Pi9 on line 3 array(0) { } array(0) { }
Output for 4.4.9
Warning: preg_match(): Compilation failed: unrecognized character after (? or (?- at offset 15 in /in/b5Pi9 on line 3 array(0) { } array(0) { }
Output for 4.3.0 - 4.3.10
Warning: Compilation failed: unrecognized character after (? at offset 15 in /in/b5Pi9 on line 3 array(0) { } array(0) { }