How to search Array for multiple values in PHP?

Question

I need to get the keys from values that are duplicates. I tried to use array_search and that worked fine, BUT I only got the first value as a hit.

I need to get both

Answer 1

In array_search() we can read:

If needle is found in haystack more than once, the first matching key is returned. To return the keys for all matching values, use array_keys() with the optional search_value parameter instead.