array_intersect_key

(PHP 5 >= 5.1.0, PHP 7)

Computes the intersection of arrays using keys for comparison

array array_intersect_key ( array $array1, array $array2 [, array $... ] )

array_intersect_key() returns an array containing all the entries of array1 which have keys that are present in all the arguments.

Parameters:

array1

The array with master keys to check.

array2

An array to compare keys against.

...

A variable list of arrays to compare.

Returns:

Returns an associative array containing all the entries of array1 which have keys that are present in all arguments.

Examples:

array_intersect_key() 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));
?>

The above example will output:

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