note 43584 added to function.array-intersect

I think monte at ispi dot net is confused about union and intersection. The union of two arrays is the set which consists of all the elements from both arrays, the intersection is the set which consists of elements that only exist in both arrays at the same time. The code he gave simply does intersection again. Also <?php $arr1 = array(1,2,3,4); $arr2 = array(2,4,6,8); $union = array_intersect($arr2, array_intersect($arr1, $arr2)); ?> Any number of intersections with an already intersected array will always return the same array back. Thus: <?php array_intersect($arr1,$arr2) == array_intersect($arr2,array_intersect($arr1,$arr2)); ?> To get the union, this code should work: <?php $arr1 = array(1,2,3,4); $arr2 = array(1,4,9,10); $inter = array_intersection($arr1,$arr2); $union = array_diff($arr1,$inter) + $inter + $array_diff($arr2,$inter); ?> ---- Manual Page -- http://www.php.net/manual/en/function.array-intersect.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+43584 Delete -- http://master.php.net/manage/user-notes.php?action=delete+43584&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+43584&report=yes Search -- http://master.php.net/manage/user-notes.php