如何将 map 的键和值复制到对集合

Question

Hello all i am trying to transfer my data from the map to the set of pair that's my test code

#include <iostream>
#include <unordered_map>
#include <map>
#include <algorithm>
#include <vector>




using namespace std;

int main() {


    string command;

    int resource;
   map<string, int> map;
   set< pair<string, int> > s;

   while (std::cin >> command && command != "stop" && std::cin >> resource)
    {
        map[command] += resource;

    }


    return 0;
}

When the while loop finish and the map is filled. How to transfer the data or copy it to the set of pair?

Thank you in advance

Answer 1

The set constructor actually handles this all for you, so you can just do:

std::set<std::pair<std::string, int>> s(m.begin(), m.end());

See it in action here: https://ideone.com/Do0LOW

(Also, you probably shouldn't name your variable map the same as a type. This is even more of an issue when you're using namespace std like that).

Answer 2

You can use the set constructor that takes the map as a range.

std::set<std::pair<std::string, int>> s {map.begin(), map.end()};

If your set already exists, then you can use copy .

std::copy(map.begin(), map.end(), std::inserter(s, s.end()));