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run code in 300+ PHP versions simultaneously
<?php preg_match("/^(aaa)(?:(x)?)/", "aaay", $matches, PREG_UNMATCHED_AS_NULL); var_dump($matches);
Output for 7.4.0 - 7.4.26, 8.0.0 - 8.0.13, 8.1rc1 - rc3
array(3) { [0]=> string(3) "aaa" [1]=> string(3) "aaa" [2]=> NULL }
Output for 7.2.0 - 7.2.33, 7.3.0 - 7.3.33
array(2) { [0]=> string(3) "aaa" [1]=> string(3) "aaa" }
Output for 7.1.0 - 7.1.25
Notice: Use of undefined constant PREG_UNMATCHED_AS_NULL - assumed 'PREG_UNMATCHED_AS_NULL' in /in/1ulVZ on line 3 Warning: preg_match() expects parameter 4 to be integer, string given in /in/1ulVZ on line 3 NULL

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