How does a reference-counting smart pointer's reference counting work?

Question

In other words, how does the implementation keeps track of the count?

Is there a map-like object maintained which is accessible by all the shared_ptr in

Answer 1

Each smart pointer object contains a shared reference count - one for every raw pointer.

You could take a look at this article. This implementation stores these in a separate object which is copied around. You could also take a look at boost's documentation or take a look at the Wikipedia article on smart pointers.