Best way to check for one of two values in an array in PHP
If you want to verify that either value is in the $array_under_test, array_intersect may not be the best option. It will continue to test for collisions even after it finds a match. 

For two search strings you can just do:

if (in_array('a', $array_under_test) || in_array('b', $array_under_test)) {
  // Success!
}


This will stop searching if 'a' is found in the $array_under_test.

For more than two values, you can use a loop:

foreach ($match_array as $value) {
  if (in_array($value, $array_under_test)) {
    // Success!
    break;
  }
}