# array_udiff

(PHP 5)

array_udiff — Computes the difference of arrays by using a callback function for data comparison

### Description

array array_udiff ( array `$array1` , array `$array2` [, array `$ ...` ], callback `$data_compare_func` )

array_udiff() returns an array containing all the values of `array1` that are not present in any of the other arguments. Note that keys are preserved. For the comparison of the data `data_compare_func` is used. It must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second. This is unlike array_diff() which uses an internal function for comparing the data.

Example#1 array_udiff() example

`<?php
class cr {
private $priv_member;
function cr($val)
{
$this->priv_member = $val;
}
function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);
$result = array_udiff($a, $b, array("cr", "comp_func_cr"));
print_r($result);
?>`

The above example will output:

    Array
    (
        [0.5] => cr Object
            (
                [priv_member:private] => 12
            )

        [0] => cr Object
            (
                [priv_member:private] => 23
            )

    )

> 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_udiff($array1[0], $array2[0], "data_compare_func");.

See also array_diff(), array_diff_assoc(), array_diff_uassoc(), array_udiff_assoc(), array_udiff_uassoc(), array_intersect(), array_intersect_assoc(), array_uintersect(), array_uintersect_assoc() and array_uintersect_uassoc().