3v4l.org

run code in 300+ PHP versions simultaneously
<?php $pattern = "hello[/name/hello[/second]][/bye]"; if (preg_match_all('/\[((?:[^\[\]]*|(?R))*)\]/', $pattern, $matches)) { print_r($matches); }
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.31, 8.2.0 - 8.2.26, 8.3.0 - 8.3.15, 8.4.1 - 8.4.2
Array ( [0] => Array ( [0] => [/name/hello[/second]] [1] => [/bye] ) [1] => Array ( [0] => /name/hello[/second] [1] => /bye ) )
preferences:
52.89 ms | 410 KiB | 5 Q