Out 参数的经典应用-判断用户的登入

//判断用户的登入
        public static bool Login(string loginId, string loginPwd,out User validUser)
        {
            User user = UserService.GetUserByLoginId(loginId);
            if (user != null)
            {
                if (user.LoginPwd == loginPwd)
                {
                    validUser = user;
                    return true;
                }
            }
            validUser = null;
            return false;
        }