array_rand

 mixed array_rand ( array $input [, int $num_req = 1 ] ) 

説明

Picks one or more random entries out of an array, and returns the key (or keys) of the random entries.

戻り値

If you are picking only one entry, array_rand() returns the key for a random entry. Otherwise, it returns an array of keys for the random entries. This is done so that you can pick random keys as well as values out of the array.