Online PHP editor | output for GO0lS

<?php $a = [ 0 => [ "qty" => 1, "name" => "Guide, interlocked slats, R Commodity code: 39239000 / Country of origin: PL. Delivery note 838174147 from 12.09.2019 PC 1,50/ 10", ], 1 => [ "qty" => null, "name" => "Guide, interlocked slats, L Commodity code: 39239000 / Country of origin: PL. Delivery note 838174147 from 12.09.2019 PC", ], 2 => [ "qty" => null, "name" => "Bottom groove set L + R Commodity code: 39239000 / Country of origin:", ] ]; $keys = $a[0]; foreach ($a as $item) { foreach ($item as $key => $value) { if ($value === null) { unset($keys[$key]); } if (empty($keys)) { break 2; } } } print_r(array_keys($keys));