How do I handle circular references with shared_ptr in C++?

How do I handle circular references with shared_ptr in C++?

Circular references can lead to memory leaks when using shared_ptr. You can use weak_ptr to break the cycle.

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;
    std::weak_ptr<Node> prev;
};

int main() {
    auto node1 = std::make_shared<Node>();
    auto node2 = std::make_shared<Node>();
    node1->next = node2;
    node2->prev = node1;
    return 0;
}

What happens if I don't use weak_ptr in this case?

If you don't use weak_ptr, both nodes will keep each other alive, preventing their memory from being freed, leading to a memory leak.

Are there any best practices for using shared_ptr and weak_ptr?

Yes, always prefer weak_ptr for back-references in circular structures, and avoid using raw pointers whenever possible.