What are some examples of weak pointers in C++?

Can you explain what weak pointers are in C++?

Weak pointers in C++ are smart pointers that do not own the object they point to, preventing circular references.

Can you give me an example of how to use a weak pointer?

Sure! Here's a simple example:

#include <iostream>
#include <memory>

class MyClass {
public:
    MyClass() { std::cout << "MyClass created" << std::endl; }
    ~MyClass() { std::cout << "MyClass destroyed" << std::endl; }
};

int main() {
    std::shared_ptr<MyClass> sharedPtr = std::make_shared<MyClass>();
    std::weak_ptr<MyClass> weakPtr = sharedPtr;

    if (auto tempPtr = weakPtr.lock()) {
        std::cout << "Weak pointer is valid" << std::endl;
    } else {
        std::cout << "Weak pointer is expired" << std::endl;
    }
    return 0;
}

What happens if the shared pointer is deleted?

If the shared pointer is deleted, the weak pointer will no longer be valid. Calling lock() on the weak pointer will return a null pointer.

Are there any performance considerations when using weak pointers?

Yes, weak pointers can help avoid memory leaks and circular references, but they may introduce slight overhead due to reference counting.