How do I use weak_ptr in C++?

How do I use weak_ptr in C++?

In C++, weak_ptr is used to prevent circular references in shared_ptr. It allows you to reference an object without owning it.

Can you give me an example of how to implement weak_ptr?

Sure! Here's a simple example:

#include <iostream>
#include <memory>

class Node {
public:
    std::shared_ptr<Node> next;
    Node() { std::cout << "Node created" << std::endl; }
    ~Node() { std::cout << "Node destroyed" << std::endl; }
};

int main() {
    std::shared_ptr<Node> node1 = std::make_shared<Node>();
    std::weak_ptr<Node> weakNode = node1;
    if (auto sharedNode = weakNode.lock()) {
        std::cout << "Weak pointer is valid" << std::endl;
    }
    return 0;
}

What happens if the object pointed to by weak_ptr is deleted?

If the object is deleted, the weak_ptr becomes expired. You can check this using the expired() method before trying to lock it.

Are there any performance considerations when using weak_ptr?

Yes, weak_ptr has a slight overhead compared to raw pointers, but it helps manage memory more safely, especially in complex data structures.