Pointer to a map

For instance:

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

int main() {
  std::map<int, std::string> * mapping = new std::map<int, std::string>();
  (*mapping)[1] = "test";
  std::cout << (*mapping)[1] <<std::endl;
}

With the introduction of "at" function in c++ 11, you can use mappings->at(key) instead of (*mapping)[key].

Keep in mind that this api will throw out_of_range exception if the key is not already available in the map.

Not much difference except that you have to use -> for accessing the map members. i.e.

mapping->begin() or mapping->end()

If you don't feel comfortable with that then you can assign a reference to that and use it as in the natural way:

map<int, string> &myMap = *mappings;  // 'myMap' works as an alias
                ^^^^^^^^

Use myMap as you generally use it. i.e.

myMap[2] = "2";
myMap.begin() or myMap.end();

Use the pointer just like you use any other pointer: dereference it to get to the object to which it points.

typedef std::map<int, string>::iterator it_t;

it_t   it1 = mappings->begin();   // (1)
it_t   it2 = (*mappings).begin(); // (2)

string str = (*mappings)[0];      // (3)

Remember that a->b is — mostly — equivalent to (*a).b, then have fun!

^{(Though this equivalence doesn't hold for access-by-index like (*a)[b], for which you may not use the -> syntax.)}