How change the key in the map?

[Yukon]

I need make it without loop (for, while...).
Only by methods STL.
Loop accecible only for print the results.

class Obj
{
public:
  string get_str() const;
  int get_int() const;
private:
  Obj( string my_str_, int my_int_ );
  string my_str;
  int my_int;
}
 

class Map_obj
{
public:
  void insert_obj( string my_str, int my_int );
  void print_ordre_by_str() const;
  void print_ordre_by_int() const;
  void del_by_int( int i );
private:
  map<string, Obj*> my_map;
}
 

For insert_obj() I finished:

void Map_obj::insert_obj( string my_str, int my_int )
{
    Obj* ptr = new Obj( my_str, my_int );
     my_map.insert( make_pair<string> ( my_str, ptr ) );
}
 

For print_ordre_by_str() i don't need make order.
Because it's order by string by default.

map <string, Obj*>::const_iterator ptr = my_map.begin();
while ( ptr != my_map.end() )
{
    cout << *ptr->second << endl;
    ptr++;
}
 

But i don't know how realise:
print_ordre_by_int() //print the Obj in order by int
and
del_by_int( int i ) //delete the Obj with searched int