C++17 STL Cookbook

How it works...

Weak pointers provide us a way to point at an object maintained by shared pointers without incrementing its use counter. Okay, a raw pointer could do the same, but a raw pointer cannot tell us if it is dangling or not. A weak pointer can!

In order to understand how weak pointers as an addition to shared pointers work, let's directly jump to an illustrating diagram:

The flow is similar to the diagram in the recipe about shared pointers. In step 1, we have two shared pointers and a weak pointer pointing to the object of type Foo. Although there are three objects pointing to it, only the shared pointers manipulate its use counter, ...