PHP Manual
Prev |  | Next

# array_diff_key

(PHP 5 >= 5.1.0RC1)

array_diff_key -- Computes the difference of arrays using keys for comparison

## Description

array array_diff_key ( array array1, array array2 [, array ...] )

array_diff_key() returns an array containing all the values of `array1` that have keys that are not present in any of the other arguments. Note that the associativity is preserved. This function is like array_diff() except the comparison is done on the keys instead of the values.

Example 1. array_diff_key() example

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

The above example will output:

    array(2) {
      ["red"]=>
      int(2)
      ["purple"]=>
      int(4)
    }

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.

> Note: Please note that this function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using `array_diff_key($array1[0], $array2[0]);`.

See also array_diff(), array_udiff() array_diff_assoc(), array_diff_uassoc(), array_udiff_assoc(), array_udiff_uassoc(), array_diff_ukey(), array_intersect(), array_intersect_assoc(), array_intersect_uassoc(), array_intersect_key() and array_intersect_ukey().

Prev | Home | Next
array_diff_assoc | Up | array_diff_uassoc