there is a function that converts numbers from decimal to roman

decToRoman.cpp

#include <map>
#include <string>

std::string decimalToRoman(int n) {
	std::string roman = "";
	const std::map<int, std::string> rd = {
		{1000, "M"},
		{900, "CM"},
		{500, "D"},
		{400, "CD"},
		{100, "C"},
		{90, "XC"},
		{50, "L"},
		{40, "XL"},
		{10, "X"},
		{9, "IX"},
		{5, "V"},
		{4, "IV"},
		{1, "I"},
		{0, "0"} // IS NEVER USED
	};
	// doing like this because of sorted structure of std::map, { 0: "0" } too
	for (auto it = end(rd); it != begin(rd); --it) {
		while (n >= (*it).first) {
			n -= (*it).first,
			roman += (*it).second;
		}
	}
	return roman;
}