c++ - 如何获取返回值并将其设置为 “x”？

我正在为学校工作，但遇到了问题。请理解，我对c++和编程一般还是很陌生(过去的经验只是一点点HTML)。无论如何，这是我的问题。

例如，我是一名在校学生，我想去吃午餐。我去吃午餐，然后花掉大约x钱，然后将那笔钱带回主要功能。

    int lunch(int moneyL)
    {
        std::cout << Here is lunch! 4 bucks please";
        moneyL - 4
        return moneyL;
    }

    int main()
    {
        std::cout << "You are given 5 dollars to eat lunch" << std::endl;
        int money = 5;
        std::cout << "Lets go to lunch";
        Lunch(money)
    }

同样，我的问题是(如果我感到困惑)如何将int main中的钱设置为午餐中带走的钱？

谢谢

最佳答案

有多种解决方法:

解决方案1(按返回值):

int lunch(int moneyL)
{
    std::cout << "Here is lunch! 4 bucks please\n";
    moneyL = moneyL - 4;
    return moneyL;
}

int main()
{
    std::cout << "You are given 5 dollars to eat lunch" << std::endl;
    int money = 5;
    std::cout << "Lets go to lunch\n";
    money = lunch(money)
}

解决方案2(按引用):

void lunch(int& moneyL)
{
    std::cout << "Here is lunch! 4 bucks please\n";
    moneyL = moneyL - 4;
}

int main()
{
    std::cout << "You are given 5 dollars to eat lunch" << std::endl;
    int money = 5;
    std::cout << "Lets go to lunch\n";
    lunch(money);
}