3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [ 1 => [1, 12, 2], 2 => [1, 13, 3], 3 => [1, 12, 2], 4 => [1], 5 => [1] ]; array_walk_recursive($array, function($v)use(&$output) { if (isset($output[$v])) { ++$output[$v]; } else { $output[$v] = 1; } }); var_export($output);
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array ( 1 => 5, 12 => 2, 2 => 2, 13 => 1, 3 => 1, )
preferences:
112.94 ms | 408 KiB | 5 Q