#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <locale>
using namespace std;

class commas: public numpunct<char> {
public:
	explicit commas(size_t r = 0): numpunct<char>(r) {}
protected:
	char do_thousands_sep() const {return ',';}
	string do_grouping() const {return "\x03";}
};

inline void print() {
	cout << setw(12) << 123456789
		<< "   " << right << setw(15) << 123456789.123 << "\n";
}

int main()
{
	cout << fixed  //to prevent double from appearing in scientific notation
		<< setprecision(3);

	print();

	const locale loc(locale(), new commas);
	cout.imbue(loc);
	print();

	return EXIT_SUCCESS;
}