array_udiff

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

&reftitle.description; `array` `array_udiff` `array` `array` `array` `arrays` `callable` `value_compare_func`

Computes the difference of arrays by using a callback function for data comparison. This is unlike `array_diff` which uses an internal function for comparing the data.

&reftitle.parameters;

`array`

- The first array.

`arrays`

- Arrays to compare against.

`value_compare_func`

- &sort.callback.description; &sort.callback.description.presort;
&reftitle.returnvalues;

Returns an array containing all the values of `array` that are not present in any of the other arguments.

&reftitle.examples;

### `array_udiff` example using stdClass Objects

    <?php
    // Arrays to compare
    $array1 = array(new stdClass, new stdClass,
                    new stdClass, new stdClass,
                   );

    $array2 = array(
                    new stdClass, new stdClass,
                   );

    // Set some properties for each object
    $array1[0]->width = 11; $array1[0]->height = 3;
    $array1[1]->width = 7;  $array1[1]->height = 1;
    $array1[2]->width = 2;  $array1[2]->height = 9;
    $array1[3]->width = 5;  $array1[3]->height = 7;

    $array2[0]->width = 7;  $array2[0]->height = 5;
    $array2[1]->width = 9;  $array2[1]->height = 2;

    function compare_by_area($a, $b) {
        $areaA = $a->width * $a->height;
        $areaB = $b->width * $b->height;

        if ($areaA < $areaB) {
            return -1;
        } elseif ($areaA > $areaB) {
            return 1;
        } else {
            return 0;
        }
    }

    print_r(array_udiff($array1, $array2, 'compare_by_area'));
    ?>

&example.outputs;

    Array
    (
        [0] => stdClass Object
            (
                [width] => 11
                [height] => 3
            )

        [1] => stdClass Object
            (
                [width] => 7
                [height] => 1
            )

    )

### `array_udiff` example using DateTime Objects

    <?php
    class MyCalendar {
        public $free = array();
        public $booked = array();

        public function __construct($week = 'now') {
            $start = new DateTime($week);
            $start->modify('Monday this week midnight');
            $end = clone $start;
            $end->modify('Friday this week midnight');
            $interval = new DateInterval('P1D');
            foreach (new DatePeriod($start, $interval, $end) as $freeTime) {
                $this->free[] = $freeTime;
            }
        }

        public function bookAppointment(DateTime $date, $note) {
            $this->booked[] = array('date' => $date->modify('midnight'), 'note' => $note);
        }

        public function checkAvailability() {
            return array_udiff($this->free, $this->booked, array($this, 'customCompare'));
        }

        public function customCompare($free, $booked) {
            if (is_array($free)) $a = $free['date'];
            else $a = $free;
            if (is_array($booked)) $b = $booked['date'];
            else $b = $booked;
            if ($a == $b) {
                return 0;
            } elseif ($a > $b) {
                return 1;
            } else {
                return -1;
            }
        }
    }

    // Create a calendar for weekly appointments
    $myCalendar = new MyCalendar;

    // Book some appointments for this week
    $myCalendar->bookAppointment(new DateTime('Monday this week'), "Cleaning GoogleGuy's apartment.");
    $myCalendar->bookAppointment(new DateTime('Wednesday this week'), "Going on a snowboarding trip.");
    $myCalendar->bookAppointment(new DateTime('Friday this week'), "Fixing buggy code.");

    // Check availability of days by comparing $booked dates against $free dates
    echo "I'm available on the following days this week...\n\n";
    foreach ($myCalendar->checkAvailability() as $free) {
        echo $free->format('l'), "\n";
    }
    echo "\n\n";
    echo "I'm busy on the following days this week...\n\n";
    foreach ($myCalendar->booked as $booked) {
        echo $booked['date']->format('l'), ": ", $booked['note'], "\n";
    }
    ?>

&example.outputs;

    I'm available on the following days this week...

    Tuesday
    Thursday

    I'm busy on the following days this week...

    Monday: Cleaning GoogleGuy's apartment.
    Wednesday: Going on a snowboarding trip.
    Friday: Fixing buggy code.

&reftitle.notes;

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");`.

&reftitle.seealso;

- `array_diff`
- `array_diff_assoc`
- `array_diff_uassoc`
- `array_udiff_assoc`
- `array_udiff_uassoc`
- `array_intersect`
- `array_intersect_assoc`
- `array_uintersect`
- `array_uintersect_assoc`
- `array_uintersect_uassoc`