How are automatic memory management mechanisms implemented in C++, and what are smart pointers?

In C++, automatic memory management is implemented using smart pointers — special wrapper classes over regular pointers that automatically manage the lifetime of objects and memory deallocation.

Main types of smart pointers:

• std::unique_ptr — owns the object exclusively, does not allow copying, automatically deletes the object when it goes out of scope.
• std::shared_ptr — implements reference counting, the object is deleted when the last shared_ptr stops referencing it.
• std::weak_ptr — a weak reference to an object, does not affect its lifetime, used to prevent cyclic dependencies.

Example of using std::unique_ptr:

#include <memory>
#include <iostream>

int main() {
    std::unique_ptr<int> ptr = std::make_unique<int>(42);
    std::cout << *ptr << std::endl; // outputs 42
    // memory will be freed automatically when exiting main
}

Thus, smart pointers help avoid memory leaks and errors with double deletion, simplifying resource management.