cppSTLBasics

#include <iostream>
#include <memory>
#include <array>
#include <vector>
#include <forward_list>
#include <algorithm>

class Item
{
    std::string name;
    std::weak_ptr<Item> pair;
public:
    const int size{ 34 };
    Item(std::string nameP) : name{ nameP } { std::cout << "Item created for " << this << '\n'; }

    Item(const Item& it) = delete;
    Item& operator=(const Item& it) = delete;


    const std::string& getName()const { return name; };

    void print()const { std::cout << "Item # " << this << " named " << name << '\n'; }
    ~Item() { std::cout << "Item destroyed for " << this << '\n'; }

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

    friend bool addPair(std::shared_ptr<Item>& left, std::shared_ptr<Item>& right)
    {
        if (!left or !right)
        {
            return false;
        }

        left->pair = right;
        right->pair = left;

        std::cout << left->getName() << " paired with " << right->getName() << '\n';

        return true;
    }

    friend bool addFriend(std::shared_ptr<Item>& left, std::shared_ptr<Item>& right)
    {
        if (!left or !right)
        {
            return false;
        }

        left->pair = right;

        std::cout << right->getName() << " is friend of " << left->getName() << '\n';

        return true;
    }
};

void printItem(Item* it)
{
    it->print();
}

namespace itstep
{
    template <typename InIter, typename Func>
    void for_each(InIter begin, InIter end, Func func)
    {
        for (; begin != end; ++begin)
        {
            func(*begin);
        }
    }

    template <typename T>
    void print(T& elem)
    {
        std::cout << elem << ' ';
    }

    template <typename T>
    void mul2(T& elem)
    {
        elem *= 2;
    }

}


int main()
{
    std::array<int, 10> staticArr;
    //std::vector<int> dynArr{1,2,3,4,5,6,7,8,9,10};

    std::forward_list<int> dynArr{ 1,2,3,4,5,6,7,8,9,10 };

    auto begin{ dynArr.begin() };
    auto end{ dynArr.end() };

    //for (begin = dynArr.begin(); begin != end; ++begin)
    //{
    //  std::cout << *begin << ' ';
    //}

    auto printer{ [](auto& elem) { std::cout << elem << ' '; } };

    itstep::for_each(dynArr.begin(), dynArr.end(), printer);

    std::cout << '\n';

    //for (begin = dynArr.begin(); begin != end; ++begin)
    //{
    //  *begin *=2;
    //}
    std::for_each(dynArr.begin(), dynArr.end(), [](auto& elem) { elem *= 2; });

    std::cout << '\n';

    //for (begin = dynArr.begin(); begin != end; ++begin)
    //{
    //  std::cout << *begin << ' ';
    //}

    std::for_each(dynArr.begin(), dynArr.end(), printer);

    return 0;
}