(PHP 4 >= 4.0.1, PHP 5)
array_diff — Computes the difference of arrays
Compares array1 against array2 and returns the difference.
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) $elem2. In words: when the string representation is the same.
Note: This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using array_diff($array1[0], $array2[0]);.
This was broken in PHP 4.0.4!