php man page for array_udiff

ARRAY_UDIFF(3)								 1							    ARRAY_UDIFF(3)

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

SYNOPSIS
       array array_udiff (array  $array1, array  $array2, [array  $...], callable  $value_compare_func)

DESCRIPTION
	Computes  the  difference  of arrays by using a callback function for data comparison. This is unlike array_diff(3) which uses an internal
       function for comparing the data.

PARAMETERS
	      o $array1
		- The first array.

	      o $array2
		- The second array.

	      o $value_compare_func
		- The callback comparison function.  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)

RETURN VALUES
	Returns an array containing all the values of $array1 that are not present in any of the other arguments.

EXAMPLES
       Example #1

	      array_udiff(3) 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'));
	      ?>

	      The above example will output:

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

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

	      )

       Example #2

	      array_udiff(3) 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...

";
	      foreach ($myCalendar->checkAvailability() as $free) {
		  echo $free->format('l'), "
";
	      }
	      echo "

";
	      echo "I'm busy on the following days this week...

";
	      foreach ($myCalendar->booked as $booked) {
		  echo $booked['date']->format('l'), ": ", $booked['note'], "
";
	      }
	      ?>

	      The above example will output:

	      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.

NOTES
       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(3), array_diff_assoc(3), array_diff_uassoc(3),  array_udiff_assoc(3),  array_udiff_uassoc(3),  array_intersect(3),  array_inter-
       sect_assoc(3), array_uintersect(3), array_uintersect_assoc(3), array_uintersect_uassoc(3).

PHP Documentation Group 													    ARRAY_UDIFF(3)