3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [ ['key' => 1], ['key' => 2], ['key' => 3], ['key' => 1], ['key' => 2], ['key' => 3], ['key' => 4], ['key' => 5], ['key' => 6] ]; var_export(array_values(array_column($array, 'key', 'key')));
Output for 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.13
array ( 0 => 1, 1 => 2, 2 => 3, 3 => 4, 4 => 5, 5 => 6, )

preferences:
53.86 ms | 406 KiB | 5 Q