C++: What are smart pointers?

1#include <memory>
2
3// unique_ptr — exclusive ownership
4auto ptr1 = std::make_unique<int>(10);
5auto ptr2 = std::move(ptr1);  // Transfer
6
7// shared_ptr — shared ownership
8auto sptr1 = std::make_shared<int>(20);
9auto sptr2 = sptr1;  // ref count +1
10
11// weak_ptr — non-owning reference
12std::weak_ptr<int> wptr = sptr1;
13if (auto locked = wptr.lock()) {
14    std::cout << *locked;
15}