3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = [[["AAA", "BBB"]], [["CCC"]]]; function flatten($arr) { return array_merge(...$arr); } $arr = flatten(flatten($arr)); print_r($arr);
Output for 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 ( [0] => AAA [1] => BBB [2] => CCC )
preferences:
96.27 ms | 1615 KiB | 4 Q