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run code in 300+ PHP versions simultaneously
<?php $s = "test"; preg_match("/(?P<differentword>(test))/", $s, $matches); var_dump(array_keys($matches));
Output for 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 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
array(4) { [0]=> int(0) [1]=> string(13) "differentword" [2]=> int(1) [3]=> int(2) }

preferences:
108.44 ms | 1974 KiB | 4 Q