This is a cleaner and more modern approach (PHP 7.4+ syntax).<?php$array1 = ['blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4];$array2 = ['green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8];$result = array_intersect_ukey($array1, $array2, fn($a, $b) => $a <=> $b);var_dump($result);?>Explanation:The comparison function fn($a, $b) => $a <=> $b uses the spaceship operator directly inside the array_intersect_ukey call.The result will contain entries from $array1 whose keys also exist in $array2.Output:phpCopyEditarray(2) { ["blue"]=> int(1) ["green"]=> int(3)}