(array_intersect_ukey($a,$b,'key_compare_func')

$key2){
        return 1;
    }else{
        return -1;
    }

}
$a = array('a'=>1,'b'=>1,'c'=>2);
$b = array('a'=>1,2,3);
print_r(array_intersect_ukey($a,$b,'key_compare_func'));
Array
(
    [a] => 1
    [b] => 1
)