C++17 STL Cookbook

Dealing with weak pointers to shared objects

In the recipe about shared_ptr, we learned how useful and easy to use shared pointers are. Together with unique_ptr, they pose an invaluable improvement for code that needs to manage dynamically allocated objects.

Whenever we copy shared_ptr, we increment its internal reference counter. As long as we hold our shared pointer copy, the object being pointed to will not be deleted. But what if we want some kind of weak pointer, which enables us to get at the object as long as it exists but does not prevent its destruction? And how do we determine if the object still exists, then?

In such situations, weak_ptr is our companion. It is a little bit more complicated to use than unique_ptr and shared_ptr ...