How to traverse a map of the form pair<int,pair<int,int>> with a iterator

Question

I defined map like

map <int,pair<int,int>> hmap;

If there is a pair(2,pair(3,4)) how to get 2 3 4 values, itr->first , itr->second not working

Answer 1

If there is a pair(2,pair(3,4)) how to get 2 3 4 values [from an iterator itr to map<int,pair<int, int>> ]

I suppose

itr->first           // 2
itr->second.first    // 3
itr->second.second   // 4

Answer 2

Here is a demonstrative program with using iterators and the range-based for statement.

#include <iostream>
#include <map>

int main()
{
    std::map<int, std::pair<int, int>> hmap{ { 1, { 2, 3 } }, { 2, { 3, 4 } } };

    for (auto it = hmap.begin(); it != hmap.end(); ++it)
    {
        std::cout << "{ " << it->first
            << ", { " << it->second.first
            << ", " << it->second.second
            << " } }\n";
    }

    std::cout << std::endl;

    for (const auto &p : hmap)
    {
        std::cout << "{ " << p.first
            << ", { " << p.second.first
            << ", " << p.second.second
            << " } }\n";
    }

    std::cout << std::endl;
}

Its output is

{ 1, { 2, 3 } }
{ 2, { 3, 4 } }

{ 1, { 2, 3 } }
{ 2, { 3, 4 } }