PHP Manual: array_udiff

Description

array array_udiff_uassoc ( array array1, array array2 [, array ..., callback data_compare_func, callback key_compare_func] )

array_udiff_uassoc() returns an array containing all the values from array1 that are not present in any of the other arguments. Note that the keys are used in the comparison unlike array_diff() and array_udiff(). The comparison of arrays' data is performed by using an user-supplied callback : data_compare_func. In this aspect the behaviour is opposite to the behaviour of array_diff_assoc() which uses internal function for comparison. The comparison of keys (indices) is done also by the callback function key_compare_func. This behaviour is unlike what array_udiff_assoc() does, since the latter compares the indices by using an internal function.

Example 1. array_udiff_uassoc() 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;
    }
    
    function comp_func_key($a, $b) 
    {
        if ($a === $b) return 0;
        return ($a > $b)? 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),);

$result = array_udiff_uassoc($a, $b, array("cr", "comp_func_cr"), array("cr", "comp_func_key"));
print_r($result);
?>

The above example will output:

Array
(
    [0.1] => cr Object
        (
            [priv_member:private] => 9
        )

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

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

In our example above you see the "1" => new cr(4) pair is present in both arrays and thus it is not in the ouput from the function. Keep in mind that you have to supply 2 callback functions.

For comparison is used the user supplied callback function. 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.

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