Using custom locale for number formatting in C++

locale-demo.cpp

#include <iostream>
#include <locale>

class comma_numpunct : public std::numpunct<char> {
	virtual char do_decimal_point() const {
		return ',';
	}

	virtual char do_thousands_sep() const {
		return '.';
	}

	virtual std::string do_grouping() const {
		return "\02";
	}
};


int main() {
	std::locale comma_locale(std::locale(), new comma_numpunct);
	std::cout.imbue(comma_locale);  // imbue locale for this stream
	std::cout << 1234.234f << std::endl;
	// prints out 12.34,23

	// ... or ...

	std::locale comma_locale(std::locale(), new comma_numpunct);
	std::locale::global(comma_locale);

	// and from here onwards all streams can imbue the global locale
	std::cout.imbue(std::locale());
	std::cout << 1234.234f << std::endl;
	// prints out 12.34,23
}