//把買賣后股票信息實(shí)時(shí)寫入文件中		//注：time has been considered yet
void Update(Stock &stkObj);

//把買賣后用戶信息實(shí)時(shí)寫入文件中		//注：time has been considered yet
void Update(Guest &guestObj);

void About();
void Error();