PHP Manual: Computes the difference of arrays with additional index check, compares data by a callback function

Description

array array_udiff_assoc(array $array, array ...$arrays, callable $value_compare_func)

Computes the difference of arrays with additional index check, compares data by a callback function.

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_assoc($array1[0], $array2[0], "some_comparison_func");.

Parameters

array

The first array.

arrays

Arrays to compare against.

value_compare_func

The comparison function 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.

int callback(mixed $a, mixed $b)

Caution

Returning non-integer values from the comparison function, such as float, will result in an internal cast to int of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.

Caution

The sorting callback must handle any value from any array in any order, regardless of the order they were originally provided. This is because each individual array is first sorted before being compared against other arrays. For example:

<?php
$arrayA = ["string", 1];
$arrayB = [["value" => 1]];
// $item1 and $item2 can be any of "string", 1 or ["value" => 1]
$compareFunc = static function ($item1, $item2) {
    $value1 = is_string($item1) ? strlen($item1) : (is_array($item1) ? $item1["value"] : $item1);
    $value2 = is_string($item2) ? strlen($item2) : (is_array($item2) ? $item2["value"] : $item2);
    return $value1 <=> $value2;
};
?>

Return Values

array_udiff_assoc returns an array containing all the values from array 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. In this aspect the behaviour is opposite to the behaviour of array_diff_assoc which uses internal function for comparison.

Examples

Example #1 array_udiff_assoc example

<?php
class cr {
    private $priv_member;
    function __construct($val)
    {
        $this->priv_member = $val;
    }

    static 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),);

$result = array_udiff_assoc($a, $b, array("cr", "comp_func_cr"));
print_r($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 output from the function.

array_udiff_assoc

Description

Parameters

Return Values

Examples

See Also