What are the differences between unique_ptr, shared_ptr, and weak_ptr in C++11?

What are the differences between unique_ptr, shared_ptr, and weak_ptr in C++11?

In C++11, unique_ptr is a smart pointer that owns a dynamically allocated object exclusively. shared_ptr allows multiple pointers to share ownership of an object, while weak_ptr is used to break circular references by providing a non-owning reference to an object managed by shared_ptr.

Can you give an example of when to use each type?

Sure! Use unique_ptr when you want sole ownership of an object. Use shared_ptr when you need shared ownership, like in a resource manager. Use weak_ptr to prevent memory leaks in cases where shared_ptrs might create circular references.

What happens if I try to access a weak_ptr after the object it points to has been deleted?

If you try to access a weak_ptr after the object has been deleted, it will not throw an error, but it will return a nullptr when you try to convert it to a shared_ptr. This is a safe way to check if the object still exists.

Are there any performance implications of using these smart pointers?

Yes, there are performance implications. unique_ptr has minimal overhead, shared_ptr has more overhead due to reference counting, and weak_ptr adds some overhead for managing the weak reference. It's important to choose the right one based on your performance needs.