Check whether array has keys that don't match a list

Donny P

What is the easiest way to check if an has array keys that don’t match a particular list?

$a = array(
  [ignore_me] => "blah blah blah",
  [name] => "Don"
);

does_array_have_non_ignored_entries($a); // returns true

I can think of a ton of ways to write this function, didn’t know if PHP has a quick solution. Best one I have is this:

$length = count($a);
$ignored_entry = (in_array($a, 'ignore_me') ? 1 : 0;
if ($length - $ignored_entry > 0) {...}