map::count

Because map containers do not allow for duplicate keys, this means that the function actually returns 1 if an element with that key is found, and zero otherwise.

// map::count
#include <iostream>
#include <map>
using namespace std;

int main ()
{
  map<char,int> mymap;
  char c;

  mymap ['a']=101;
  mymap ['c']=202;
  mymap ['f']=303;

  for (c='a'; c<'h'; c++)
  {
    cout << c;
    if (mymap.count(c)>0)
      cout << " is an element of mymap.\n";
    else 
      cout << " is not an element of mymap.\n";
  }

  return 0;
}