in_arrayは配列も使える。
メモ
http://php.net/manual/ja/function.in-array.php
例3 needleが配列の場合の in_array() $a = array(array('p', 'h'), array('p', 'r'), 'o'); if (in_array(array('p', 'h'), $a)) { echo "'ph' was found\n"; } if (in_array(array('f', 'i'), $a)) { echo "'fi' was found\n"; } if (in_array('o', $a)) { echo "'o' was found\n"; }