传入对 C++ 中地图的引用

发布于 2024-10-06 22:22:47 字数 759 浏览 4 评论 0原文

我希望传递对地图的引用，而不是让地图将其放置在其他地方 - 这是我正在处理的内容：

map<string, Node> _neighbors; // Instance Variable


Node& neighbor(Node& neighbor) {
    cout << "HOST: "<< neighbor.host() << " ADDRESS: " << &neighbor << endl;
    string key = this->getKey(neighbor);

    if(!_neighbors.count(key)) {
        _neighbors[key] = neighbor;
        cout << "HOST (AFTER): "<< _neighbors[key].host() << " ADDRESS: " << &_neighbors[key] << endl;
        neighbor.neighbor(*this);
    }

    return *this;
}

输出：当我调用 n1.neighbor(n2); 时// n1 是一个 host=1 的节点，n2 是一个 host=2 的节点

HOST: 2 ADDRESS: 0x7fff5fbfe580

HOST (AFTER): 2 ADDRESS: 0x100100128

原文

I'm looking to pass in a reference to a map and NOT have map place it somewhere else - Here's what I'm working with:

map<string, Node> _neighbors; // Instance Variable


Node& neighbor(Node& neighbor) {
    cout << "HOST: "<< neighbor.host() << " ADDRESS: " << &neighbor << endl;
    string key = this->getKey(neighbor);

    if(!_neighbors.count(key)) {
        _neighbors[key] = neighbor;
        cout << "HOST (AFTER): "<< _neighbors[key].host() << " ADDRESS: " << &_neighbors[key] << endl;
        neighbor.neighbor(*this);
    }

    return *this;
}

Output:
When I call n1.neighbor(n2); // n1 is a Node with host=1 and n2 is a Node with host=2

HOST: 2 ADDRESS: 0x7fff5fbfe580

HOST (AFTER): 2 ADDRESS: 0x100100128

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凉宸 2024-10-13 22:22:47

您无法将引用存储在 STL 容器中。容器存储的是对象，而引用不是对象（另外，容器中存储的对象必须是可赋值的，而引用是不可赋值的）。

您将需要使用指针映射：

std::map<std::string, Node*>

另外，请注意所有权问题。您需要确保在所有引用它们的人都使用完这些对象之前，这些对象不会被销毁。如果您在多个位置使用了对象，请考虑使用共享所有权智能指针（例如 shared_ptr）来为您管理对象生命周期。 C++ 中的手动资源管理充满危险，应不惜一切代价避免。

You can't store references in an STL container. Containers store objects and references are not objects (in addition, the objects stored in a container must be assignable, and references are not assignable).

You'll want to use a map of pointers:

std::map<std::string, Node*>

Also, beware of ownership issues. You need to make sure that the objects are not destroyed until everyone that has a reference to them is done using them. If you have objects used in multiple places, consider using a shared ownership smart pointer, like shared_ptr, to manage object lifetimes for you. Manual resource management in C++ is fraught with peril and should be avoided at all costs.

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