array_search Searches the array for a given value and returns the corresponding key if successful mixedarray_search mixedneedle arrayhaystack boolstrict Searches haystack for needle and returns the key if it is found in the array, &false; otherwise. If needle is a string, the comparison is done in a case-sensitive manner. Prior to PHP 4.2.0, array_search returns &null; on failure instead of &false;. If the optional third parameter strict is set to &true; then the array_search will also check the types of the needle in the haystack. 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. 'blue', 1 => 'red', 2 => 'green', 3 => 'red'); $key = array_search('green', $array); // $key = 2; $key = array_search('red', $array); // $key = 1; ?> ]]> &return.falseproblem; See also array_keys, array_values, array_key_exists, and in_array.