Using array_intersect_key() to Compute Array Intersection by Keys in PHP

The array_intersect_key() function returns an array containing all the values from the first array whose keys also exist in all other arrays passed as arguments.

Parameters array1: The first array to compare. array2: The array to compare against the first array. array: Additional arrays to compare (optional).

Return Value

An array representing the intersection of the arrays based on matching keys.

Example

<?php
$array1 = array('blue'=>1,'red'=>2,'green'=>3,'purple'=>4);
$array2 = array('green'=>5,'blue'=>6,'yellow'=>7,'cyan'=>8);
var_dump(array_intersect_key($array1,$array2));
?>

Output

array(2) {
  ["blue"]=> int(1)
  ["green"]=> int(3)
}