3v4l.org

run code in 500+ PHP versions simultaneously
<?php $a = []; $a += ['a', 'b']; $a += ['c', 'd']; var_dump($a);
Output for 8.2.31 - 8.2.32, 8.3.0 - 8.3.32, 8.4.1 - 8.4.23, 8.5.0 - 8.5.8
array(2) { [0]=> string(1) "a" [1]=> string(1) "b" }
preferences:
42.42 ms | 765 KiB | 4 Q