$len = 16; $base='ABCDEFGHKLMNOPQRSTWXYZabcdefghjkmnpqrstwxyz123456789'; $max=strlen($base)-1; $activatecode=''; mt_srand((double)microtime()*1000000); while (strlen($activatecode)<$len+1) $activatecode.=$base{mt_rand(0,$max)}; echo $activatecode;