Need of weak_ptr

To understand the need for weak_ptr, we need to first understand the use case of shared_ptr which leads to a common problem called a circular link. It occurs when two or more objects reference each other using a shared_ptr. For example, if ObjectA has a shared_ptr to ObjectB and ObjectB has a shared_ptr to ObjectA, they form a circular reference. This can be problematic because neither ObjectA nor ObjectB will ever be deleted, leading to a memory leak.

Here, weak_ptr comes to the rescue by providing a way to break these circular references. It allows you to create a non-own reference to an object managed by shared_ptr without affecting the reference count or preventing the object from being deleted.

The weak_ptr is one of the smart pointers that provide the capability of a pointer with some reduced risks as compared to the raw pointer. The weak_ptr, just like shared_ptr has the capability to point to the resource owned by another shared_ptr but without owning it. In other words, they are able to create a non-owning reference to the object managed by shared_ptr.