3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = [ ['a', 'b', 'c'], ['d', 'e', 'f'], ]; array_walk_recursive($a, function(&$v) { $v = strtoupper($v); } ); print_r($a);
Output for 7.0.33, 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Array ( [0] => Array ( [0] => A [1] => B [2] => C ) [1] => Array ( [0] => D [1] => E [2] => F ) )
preferences:
145.72 ms | 403 KiB | 122 Q