Re: [PHP] array_intersect problem

[Martin Alterisio]

2006/12/25, Leo Liu <[EMAIL PROTECTED]>:

Hi,

  I try to intersect associative array and it seems to fail to do so. Can
anyone show me a walk around?

  For example I have

  array1

  Array
(
    [0] => Array
        (
            [imageID] => 1
        )

    [1] => Array
        (
            [imageID] => 2
        )

    [2] => Array
        (
            [imageID] => 3
        )

    [3] => Array
        (
            [imageID] => 4
        )
)

  And array 2

  Array
(
    [0] => Array
        (
            [imageID] => 6
        )

    [1] => Array
        (
            [imageID] => 3
        )
)

  After intersection instead of me getting 3 as a result, I got the array
1 unchanged. Seems like intersection doesn't take place at all. Anyway to
solve this problem?

  Regards,

  Leo




Reality starts with Dream

Quote from php manual, in the reference for the array_intersect function:

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

That's why array_intersect isn't working with your arrays.

If you're using PHP5 you could use array_uintersect, and compare the items
by the imageID:

   function compareByImageID($elem1, $elem2) {
       return $elem1['imageID'] - $elem2['imageID'];
   }

   $intersection = array_uinsersect($array1, $array2, 'compareByImageID');

Or you can do the following, which works in PHP4, but is not as versatile as
array_uintersect:

   class InArrayFilter {
       var $arr;

       function InArrayFilter($arr) {
           $this->arr = $arr;
       }

       function filterFunction($elem) {
           return in_array($elem, $this->arr);
       }
   }

   $filter = new InArrayFilter($array2);
   $intersection = array_filter($array1, array($filter, 'filterFunction'));