Iterating through std::maps

 Map Iterators in C++17

I'm not going to comment on whether it is right or wrong to iterate through a map but bear in mind that there are other containers that are faster to iterate through.

This snippet shows the 3 ways I know to iterate through a map and the syntax to use the data. Note that the named pair is only available since C++17.

class MyClass

{

public:

    std::map<int, int> m_map;

    MyClass():

        m_map{}

    {

    }

    void Print(const int a, const int b)

    {

        std::cout << "\ta:" << a << " b:" << b << std::endl;

    }

    void Run()

    {

        m_map[1]=2;

        m_map[2]=4;

        std::cout << "Iterator:\n";

        for (auto it = m_map.begin(); it != m_map.end(); it++)

        {

            Print(it->first, it->second);

        }

        std::cout << "Auto pair:\n";

        for (auto pr : m_map)

        {

            Print(pr.first, pr.second);

        }

        std::cout << "Named pair:\n";

        for (auto& [a,b] : m_map)

        {

            Print(a, b);

        }

    }

    /* prints:

        Iterator:

            a:1 b:2

            a:2 b:4

        Auto pair:

            a:1 b:2

            a:2 b:4

        Named pair:

            a:1 b:2

            a:2 b:4

    */

};