3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = [111,222,333]; // $a += [444,555,666]; $a += [444]; var_dump($a);
Output for 5.6.40, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.6
array(3) { [0]=> int(111) [1]=> int(222) [2]=> int(333) }

preferences:
79.87 ms | 402 KiB | 59 Q