c++ - 如何从类外修改 vector

Question

我怎样才能在类外访问私有(private) vector ？我想修改这个对象的参数。

我尝试创建 getter 并通过引用返回 vector ，但是当我尝试更改主函数中包含在 vector 中的对象的参数时， vector 中的更改未保存。

class Restaurant
{
    std::vector <Waiter> waiters_vector_;

public:
     inline std::vector<Waiter> &GetWaitersVector() { return waiters_vector_; }      

     void Restaurant::AddWaiter(Waiter tmp)
{
          waiters_vector_.push_back(tmp);
}
     Restaurant();
    ~Restaurant();
};


class Waiter
{
    int current_group_id_=0;
public:
    int GetCurrentGroupId()
{
    return current_group_id_;
}

void SetCurrentGroupId(int tmp)

{
    current_group_id_ = tmp;
}

    Waiter();
    ~Waiter();
};


int main()
{  

    Restaurant restaurant1;
    Waiter w1, w2, w3;
    restaurant1.AddWaiter(w1);
    restaurant1.AddWaiter(w2);
    restaurant1.AddWaiter(w3);

    for (Waiter element : restaurant1.GetWaitersVector())
{
        element.SetCurrentGroupId(123);
}

    for (Waiter element : restaurant1.GetWaitersVector())
{
        std::cout << element.GetCurrentGroupId() << std::endl;
}

}

结果:000

Answer 1

你的两个 for 循环都在复制

for (Waiter element : restaurant1.GetWaitersVector())

你想修改对实际对象的引用

for (Waiter& element : restaurant1.GetWaitersVector())