Question

Array declaration: $uids = array();

Next these arrays may or may not be created:

$uids['locations'];
$uids['ages'];
$uids['genders'];

If at least 2 of them are created I want to calculate the intersect. If all 3 are created I want the intersect of all 3.

So, I may want to calculate the intersect of $uids['locations'] and $uids['ages'] or the intersect of $uids['ages'] and $uids['genders'], etc.

If put all 3 arrays in array_intersect then I get errors if one of them is not an array. I’m not sure how to handle this without an awful lot of if:else statements and think there is a better way.

Answer 1

If you know that you don’t have more array keys than the ones specified, you can use this:

$intersect = array();
if (count($uids) > 1) {
    $intersect = call_user_func_array('array_intersect', $uids);
}

Otherwise you could try this one:

$_uids = array_intersect_key($uids, array(
    'locations' => 1,
    'ages' => 1,
    'genders' => 1,
));
if (count($uids) > 1) {
    $intersect = call_user_func_array('array_intersect', $_uids);
}