How does automatic memory release occur when there are no strong references to objects in the system?

In C/C++, automatic memory release does not happen as in garbage-collected languages because memory management is mostly manual. However, if we talk about automatic memory release when there are no strong references, this is a concept from managed languages with garbage collection.

In reference counting systems, when strong references to an object disappear (reference count drops to zero), the object is automatically destroyed and memory is freed.

In C++, this is implemented via smart pointers, e.g., std::shared_ptr:

#include <memory>

void example() {
    std::shared_ptr<int> ptr1 = std::make_shared<int>(10); // reference count = 1
    {
        std::shared_ptr<int> ptr2 = ptr1; // reference count = 2
    } // ptr2 is destroyed, reference count = 1
    // When ptr1 goes out of scope, reference count becomes 0, memory is freed
}

Thus, automatic memory release occurs when the system tracks the number of strong references and frees memory when there are none.