Explain the working principle of the shared_ptr smart pointer in C++ and its advantages.

shared_ptr is a smart pointer in C++ that implements reference counting for a dynamically allocated object. It keeps track of the number of active owners of the object and automatically deletes the object when the last shared_ptr pointing to it is destroyed or reassigned.

Advantages:

• Automatic management of the object's lifetime, preventing memory leaks.
• Allows multiple parts of a program to share ownership of the object.
• Safe in exception scenarios, as memory is freed automatically.

Example usage:

#include <memory>
#include <iostream>

int main() {
    std::shared_ptr<int> p1 = std::make_shared<int>(42);
    {
        std::shared_ptr<int> p2 = p1; // reference count increases
        std::cout << *p2 << std::endl; // output: 42
    } // p2 goes out of scope, reference count decreases
    std::cout << *p1 << std::endl; // object still alive
} // p1 goes out of scope, object is deleted