C / C++ / MFC

#include <iostream>
#include <locale>
#include <string>
 
using namespace std;
 
class my_punct:public std::numpunct<char>
{
  protected:
    char do_thousands_sep() const {return ',';}
    std::string do_grouping() const {return "\3";}
  public:
    my_punct():numpunct<char>(){}
};
 
int main(){
  locale  loc = cout.getloc(); // get current locale.
  locale new_loc=_ADDFAC(loc,new my_punct);        
  cout.imbue(new_loc); // use new_loc        
  cout <<1000000 << endl;
  cout.imbue(loc);        // restore the locale to normal
}