Best way to check for one of two values in an array in PHP

Question

I want to see if one of two values (a, b) are in an array. Here's my current thought:

$match_array = array('a','b');
$array_under_test = array('b', 'd', 'f');
if (array_intersect($match_array, $array_under_test)) {
 // Success!
}

Any better implementations?

Answer 1

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;
 }
}

Answer 2

In addition to p.w.s.g's answer (which seems fine):

If you have lots of values you need to find, you can use a hash:

// the values go into keys of the array
$needles = array('value1' => 1, 'value2' => 1, 'value3' => 1);
$haystack = array('test', 'value1', 'etc');
// only go through the array once
$found = false;
foreach($haystack as $data) {
 if (isset($needles[$data])) {
 $found = true; break;
 }
 }

It's worth doing this if you search $haystack a lot of times.