For Karen: OutputIterator example for unordered_map

inserter.cc

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

int main() {

  // Empty int,string map
  std::unordered_map<int, std::string> m;

  // OutputIterator for inserting elements into the map
  auto out = std::inserter(m, std::end(m));

  // Just some data (note the duplicate 1 key)
  std::vector<std::pair<int, std::string>> v{{1, "a"}, {2, "b"}, {1, "c"}};

  // Copy the dummy data "into" the OutputIterator (which inserts into the map)
  std::copy(std::begin(v), std::end(v), out);

  // Print map (note how we get the first 1,a pair since insert only inserts if the element is not already present)
  for (const auto& each : m)
    std::cout << each.first << " : "  << each.second << "\n";

  // 2 : b
  // 1 : a
}