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

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

# array_udiff_assoc

(PHP 5, PHP 7, PHP 8)

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

### Description

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

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.

  callback(mixed `$a`, mixed `$b`): int
  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.

### 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

    <?phpclass 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.

### See Also

- array_diff() - Computes the difference of arrays
- array_diff_assoc() - Computes the difference of arrays with additional index check
- array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
- array_udiff() - Computes the difference of arrays by using a callback function for data comparison
- array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
- array_intersect() - Computes the intersection of arrays
- array_intersect_assoc() - Computes the intersection of arrays with additional index check
- array_uintersect() - Computes the intersection of arrays, compares data by a callback function
- array_uintersect_assoc() - Computes the intersection of arrays with additional index check, compares data by a callback function
- array_uintersect_uassoc() - Computes the intersection of arrays with additional index check, compares data and indexes by separate callback functions