PV913weak_ptr

#include<iostream>
#include <chrono>

class Element
{
    int val;
    std::weak_ptr<Element> pair;
public:
    Element(int valP) : val{ valP } { std::cout << "Element constructed for " << this << '\n'; };
    Element() : Element{ 0 } {};
    ~Element(){ std::cout << "Element destructed for " << this << '\n'; };
    int getVal() const { return val; };

    friend bool addPair(std::shared_ptr<Element>& lhs, std::shared_ptr<Element>& rhs)
    {
        if (!lhs or !rhs)
        {
            return false;
        };

        lhs->pair = rhs;
        rhs->pair = lhs;

        std::cout << lhs->getVal() << " paired with " << rhs->getVal() << '\n';

        return true;
    }
    const std::shared_ptr<Element> getPair()const { return pair.lock(); };
};



int main()
{
    srand(time(nullptr));

    std::shared_ptr<Element> One{ std::make_shared<Element>(1) };//[1 -> 1]
    std::shared_ptr<Element> Two{ std::make_shared<Element>(2) };//[2 -> 1]
    std::cout << "One " << One->getVal() << '\n';
    std::cout << "Two " << Two->getVal() << '\n';
    addPair(One, Two);// [2 -> 1], [1 -> 1]

    std::shared_ptr<Element> onePair{ One->getPair() };//[2 -> 2][2 -> 1][2 -> 2]
    std::shared_ptr<Element> twoPair{ Two->getPair() };//[1 -> 2][1 -> 1][1 -> 2]

    std::cout << (One.get() == twoPair.get()) << '\n';
    std::cout << (Two.get() == onePair.get()) << '\n';

    std::cout << "One's pair is -> " << onePair->getVal() << '\n';
    std::cout << "Two's pair is -> " << twoPair->getVal() << '\n';

}// Two destructed! [2 -> 0] Element(2) destructed! , One destructed! [1 -> 0] Element(1) destructed!