Question

Currently, this is what I do to check if all keys of an array $A are within a subset of another array $B.

$B = array('a', 'b', 'c', 'd');

if(array_keys($A) == array_intersect(array_keys($A), $B))
{
 action if true
}

I am wondering if there is a more straight forward way of doing this, something like the in_array() function.

Usage Example:

Checking the $_POST array to ensure that all keys matches a dynamic form and filter out extra keys if the form is hacked.

Answer 1

if (array_diff_key($A, array_flip($B))) {
    // there are keys in $A that are *not* in $B!
}

or possibly:

if (array_diff_key(array_flip($B), $A)) {
    // not all of the keys in $B are in $A!
}