using less<string>...

Hi,

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#include <iostream>
#include <string>
#include <map>
using namespace std;

int main()
{
     string name;
     int pop;

     string states[] = { "Wyoming", "Colorado", "Nevada",
         "Montana", "Arizona", "Idaho"};
     int pops[] = { 470, 2890, 800, 787, 2718, 944 };

     map<string, int, less<string> > mapStates;

// Try replacing the above with:
// map<string, int> mapStates;

     map<string, int, less<string> >::iterator iter; //iterator

     for(int j=0; j<6; j++)
         {
         name = states[j]; //get data from arrays
         pop = pops[j];
         mapStates[name] = pop; //put it in map
         }
     cout << "Enter state: "; //get state from user

     cin >> name;
     pop = mapStates[name]; //find population
     cout << "Population: " << pop << ",000\n";

     cout << endl; //display entire map
     for(iter = mapStates.begin(); iter != mapStates.end(); iter++)
         cout << (*iter).first << ' ' << (*iter).second << ",000\n";
     return 0;
}

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The question is: I don't see any difference between:

     map<string, int, less<string> > mapStates;

and

     map<string, int> mapStates;

I tried to google around a bit and found that both lines call the map
constructor to create a map<string, int> and the less<string> is a
comparison function - a 'weak ordering'. Can I see how less<string> is
defined somewhere?

Why don't I see any difference between both methods? Is less<string>
default? Is there also a more<string>-function?

So I also tried to look for it at www.cppreference.com which has some
nice descriptions but I couldn't find it...

Can anyone clarify this issue to me?

Best regards / Med venlig hilsen
Martin JHrgensen

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