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array_intersect_key

Computes the intersection of arrays using keys for comparison (PHP 5 >= 5.1.0)
array array_intersect_key ( array array1, array array2 [, array ...] )

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

Parameters

array1

The array with master keys to check.

array2

An array to compare keys against.

array

A variable list of arrays to compare.

Return Values

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

Examples

Example 250. 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)
}


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 array1.

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.