Printing contents of sets included in a map - c++

Question

I am writing a program that reads team names from a file and divides them into groups. Each group of size 4. I am using a:
map<int, set<string> > groups
Assume the team names to be countries names.
Now after entering all the team names into the resp. groups I want to print the contents of each group and this is where I am getting stuck.
Here is the full working code, I have written so far.
#include<iostream>
#include<vector>
#include<ctime>
#include<cstdlib>
#include<algorithm>
#include<map>
#include<set>
using namespace std;
void form_groups(vector<string>);
int main(){
srand(unsigned(time(NULL)));
string team_name;
vector<string> teams;
while (cin >> team_name)
{
teams.push_back(team_name);
}
random_shuffle(teams.begin(), teams.end());
form_groups(teams);
}
void form_groups(vector<string> teams)
{
map<int, set<string> > groups;
map<int, set<string> >::iterator it;
string curr_item;
int curr_group = 1;
int count = 0;
for(int i = 0; i < teams.size(); i++)
{
curr_item = teams.at(i);
count++;
if(count == 4)
{
curr_group += 1;
count = 0;
}
groups[curr_group].insert(curr_item);
}
cout << curr_group << endl;
for(it = groups.begin(); it != groups.end(); ++it)
{
}
}

Answer 1

Your approach is fine. By using map<int, set<string> >::iterator it you can access a the given <key,value> pair with it->first and it->second. Since set<string> is a standard container itself you can use an set<string>::iterator to traverse through the elements:
map<int, set<string> >::iterator map_it;
set<string>::iterator set_it
for(map_it = groups.begin(); map_it != groups.end(); ++map_it){
cout << "Group " << it->first << ": ";
for(set_it = map_it->second.begin(); set_it != map_it->second.end(); ++set_it)
cout << *set_it << " ";
cout << endl;
}

Answer 2

I think it is the iteration over the groups map that is your difficulty. Example of iterating over a map:
for (it = groups.begin(); it != groups.end(); it++)
{
// 'it->first' is the 'int' of the map entry (the key)
//
cout << "Group " << it->first << "\n";
// 'it->second' is the 'set<string>' of the map entry (the value)
//
for (set<string>::iterator name_it = it->second.begin();
name_it != it->second.end();
name_it++)
{
cout << " " << *name_it << "\n";
}
}

Answer 3

While iterating over a std::map<..>, it->first would give you the key, and it->second would give you the corresponding value.
You would need something like this to iterate over the map:
for(it = groups.begin(); it != groups.end(); ++it)
{
cout<<"For group: "<<it->first<<": {"; //it->first gives you the key of the map.
//it->second is the value -- the set. Iterate over it.
for (set<string>::iterator it2=it->second.begin(); it2!=it->second.end(); it2++)
cout<<*it2<<endl;
cout<<"}\n";
}