Question

Maybe I’m going insane, but I could have sworn that there was an PHP core function which took two arrays as arguments:

$a = array('1', '3');
$b = array('1'=>'apples', '2'=>'oranges', '3'=>'kiwis');

And performs an intersection where the values from array $a are checked for collisions with the keys in array $b. Returning something like

array('1'=>'apples', '3'=>'kiwis');

Does such a function exist (which I missed in the documentation), or is there a very optimized way to achieve the same thing?

Answer 1

try using array_flip {switches keys with their values} and then use array_intersect()
on your example :

$c = array_flip($b); // so you have your original b-array
$intersect = array_intersect($a,c);