PHP Reference

Description

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

array_diff() returns an array containing all the values of array1 that are not present in any of the other arguments. Note that keys are preserved.

Example 1. array_diff() example

<?php $array1 = array("a" => "green", "red", "blue", "red"); $array2 = array("b" => "green", "yellow", "red"); $result = array_diff($array1, $array2); print_r($result); ?>
Multiple occurrences in $array1 are all treated the same way. This will output :
Array ( [1] => blue )

Note: Two elements are considered equal if and only if (string) $elem1 === (string) $elem2. In words: when the string representation is 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($array1[0], $array2[0]);.

Warning

This was broken in PHP 4.0.4!