php man page for array_diff

ARRAY_DIFF(3)								 1							     ARRAY_DIFF(3)

array_diff - Computes the difference of arrays

SYNOPSIS
       array array_diff (array	$array1, array	$array2, [array  $...])

DESCRIPTION
	Compares $array1 against one or more other arrays and returns the values in $array1 that are not present in any of the other arrays.

PARAMETERS
	      o $array1
		- The array to compare from

	      o $array2
		- An array to compare against

	      o $...
		- More arrays to compare against

RETURN VALUES
	Returns an array containing all the entries from $array1 that are not present in any of the other arrays.

EXAMPLES
       Example #1

	      array_diff(3) example

	      <?php
	      $array1 = array("a" => "green", "red", "blue", "red");
	      $array2 = array("b" => "green", "yellow", "red");
	      $result = array_diff($array1, $array2);

	      print_r($result);
	      ?>

	       Multiple occurrences in $array1 are all treated the same way. This will output :

	      Array
	      (
		  [1] => blue
	      )

NOTES
       Note

	       Two  elements  are considered equal if and only if (string) $elem1 === (string) $elem2. In words: when the string representation is
	      the same.

       Note

	       This function only checks  one  dimension  of  a  n-dimensional	array.	Of  course  you  can  check  deeper  dimensions  by  using
	      array_diff($array1[0], $array2[0]);.

SEE ALSO
       array_diff_assoc(3), array_intersect(3), array_intersect_assoc(3).

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