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run code in 300+ PHP versions simultaneously
<?php var_dump(preg_match_all('/(.\K)/', 'abcd', $m), $m);
Output for 5.6.13 - 5.6.28, 7.0.0 - 7.0.20, 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
int(4) array(2) { [0]=> array(4) { [0]=> string(0) "" [1]=> string(0) "" [2]=> string(0) "" [3]=> string(0) "" } [1]=> array(4) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" [3]=> string(1) "d" } }
Output for 4.4.9, 5.2.4 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.36, 5.6.0 - 5.6.12
int(2) array(2) { [0]=> array(2) { [0]=> string(0) "" [1]=> string(0) "" } [1]=> array(2) { [0]=> string(1) "a" [1]=> string(1) "c" } }
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.8, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.3
int(0) array(2) { [0]=> array(0) { } [1]=> array(0) { } }

preferences:
297.01 ms | 402 KiB | 386 Q