decimal to roman numerals

DecimalToRoman.cpp

// DecimalToRoman.cpp : convert decimal number to Roman Numeral

#include <iostream>
#include <string>
#include <vector>

struct symbol {
	std::string name;
	int value;
};

std::vector<symbol> symbols= {
	{"M",1000},
	{"CM",900},
	{"D",500},
	{"CD",400},
	{"C",100},
	{"XC",90},
	{"L",50},
	{"XL",40},
	{"X",10},
	{"IX",9},
	{"V",5},
	{"IV",4},
	{"I",1}
};

std::string dec2Roman(int n, std::vector<symbol>::iterator i = symbols.begin());

int main(int argc, char** argv)
{
	if (argc == 2) {
		std::cout <<  dec2Roman(atoi(argv[1])) << std::endl;
		return EXIT_SUCCESS;
	}
	else {
		std::cout << "Usage: " << argv[0] << " <decimal number>" << std::endl;
		return EXIT_FAILURE;
	}
}

std::string dec2Roman(int n, std::vector<symbol>::iterator i) {

	std::string output("");

	if (i != symbols.end()) {

		while (n >= i->value) {
			n -= i->value;
			output.append(i->name);
		}

		if (n > 0)
			output.append(dec2Roman(n, ++i));
	}

	return output;
}