Question

This is my code

map<string,int> persons;

persons["B"] = 123;
persons["A"] = 321;


for(map<string,int>::iterator i = persons.begin();
    i!=persons.end();
    ++i)
{
    cout<< (*i).first << ":"<<(*i).second<<endl;
}

Expected output:

  B:123
  A:321

But output it gives is:

  A:321
  B:123

I want it to maintain the order in which keys and values were inserted in the map<string,int>.

Is it possible? Or should I use some other STL data structure? Which one?

Answer 1

There is no standard container that does directly what you want. The obvious container to use if you want to maintain insertion order is a vector. If you also need look up by string, use a vector AND a map. The map would in general be of string to vector index, but as your data is already integers you might just want to duplicate it, depending on your use case.