Online PHP editor | output for TkB6a

<?php $arr1 = [ 5 => 'PHM', 4 => 'ODM', 3 => 'N', 6 => 'M9', 10 => 'RDM9', ]; $arr2 = [ 0 => '01', 1 => '02', 2 => '03', 3 => '04', 4 => '05', 5 => '06', 6 => '07', 7 => '08', 8 => '09', 9 => '10', 10 => '11', 11 => '12', 12 => '13', ]; var_export( array_replace(array_map(fn() => null, $arr2), $arr1) ); echo "\n---\n"; var_export( array_reduce( array_keys($arr2), fn($result, $k) => $result + [$k => $arr1[$k] ?? null], [] ) ); echo "\n---\n"; $result = []; foreach ($arr2 as $k => $_) { $result[$k] = $arr1[$k] ?? null; } var_export($result);