Exchange the contents of two maps : map swap « map multimap « C++ Tutorial

1. C++ Tutorial
2. map multimap
3. map swap

#include <iostream>
#include <string>
#include <map>

using namespace std;

void show(const char *msg, map<string, int> mp);

int main() {
  map<string, int> m, m2;

  m.insert(pair<string, int>("A", 100));
  m.insert(pair<string, int>("G", 300));
  m.insert(pair<string, int>("B", 200));

  // Exchange the contents of m and m2.
  cout << "Exchange m and m2.\n";
  m.swap(m2);
  show("Contents of m: ", m);
  show("Contents of m2: ", m2);

  // Clear m.
  m.clear();
  if(m.empty()) cout << "m is now empty.";

  return 0;
}

// Display the contents of a map<string, int> by using an iterator.
void show(const char *msg, map<string, int> mp) {
  map<string, int>::iterator itr;

  cout << msg << endl;
  for(itr=mp.begin(); itr != mp.end(); ++itr)
    cout << "  " << itr->first << ", " << itr->second << endl;
  cout << endl;
}