C++: What are smart pointers?

1#include <memory>
2
3// unique_ptr — exclusive
4auto uptr = std::make_unique<int>(10);
5
6// shared_ptr — shared
7auto sptr1 = std::make_shared<int>(20);
8auto sptr2 = sptr1;  // ref count +1
9
10// weak_ptr — non-owning
11std::weak_ptr<int> wptr = sptr1;