Home/ Manual/ array / functions/ array_intersect_key

array_intersect_key

PHP function Edit on GitHub ✎

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

Computes the intersection of arrays using keys for comparison

Description

array_intersect_key(array $array, array ...$arrays): array

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

Parameters

array: The array with master keys to check.
arrays: Arrays to compare keys against.

Return Values

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

Changelog

Version	Description

Examples

array_intersect_key() example

php

<?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:

output

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

In our example you see that only the keys 'blue' and 'green' are present in both arrays and thus returned. Also notice that the values for the keys 'blue' and 'green' differ between the two arrays. A match still occurs because only the keys are checked. The values returned are those of array.

The two keys from the key => value pairs are considered equal only if (string) $key1 === (string) $key2. In other words a strict type check is executed so the string representation must be the same.