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<?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 4.4.5 - 4.4.9, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
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 4.3.11, 4.4.0 - 4.4.4, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6
Warning: preg_match(): Compilation failed: unrecognized character after (? at offset 2 in /in/jffS4 on line 8
Output for 4.3.0 - 4.3.10
Warning: Compilation failed: unrecognized character after (? at offset 2 in /in/jffS4 on line 8

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272.76 ms | 401 KiB | 456 Q