decimal_to_roman_numeral.cpp File Reference

This Programme Converts a given decimal number in the range [0,4000) to both Lower case and Upper case Roman Numeral. More...

#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>

Include dependency graph for decimal_to_roman_numeral.cpp:

Functions
std::string	fill (char c, int n)
std::string	tolowerRoman (int n)
std::string	toupperRoman (int n)
int	main ()

Detailed Description

This Programme Converts a given decimal number in the range [0,4000) to both Lower case and Upper case Roman Numeral.

Function Documentation

fill()

std::string fill	(	char	c,
		int	n )

This functions fills a string with character c, n times and returns it

Note

This can probably be replace by memcpy function.

                              {
    std::string s = "";
    while (n--) s += c;
    return s;
}

main()

int main

(

void

)

main function

           {
    int n;
    std::cout << "\t\tRoman numbers converter\n\n";
    std::cout << "Type in decimal number between 0 up to 4000 (exclusive): ";
    std::cin >> n;
    std::cout << n << " in Upper Roman Numerals is " << toupperRoman(n) << "\n";
    std::cout << n << " in Lower Roman Numerals is " << tolowerRoman(n) << "\n";
    return 0;
}

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tolowerRoman()

std::string tolowerRoman

(

int

n

)

to convert to lowercase Roman Numeral the function works recursively

                              {
    if (n < 4)
        return fill('i', n);
    if (n < 6)
        return fill('i', 5 - n) + "v";
    if (n < 9)
        return std::string("v") + fill('i', n - 5);
    if (n < 11)
        return fill('i', 10 - n) + "x";
    if (n < 40)
        return fill('x', n / 10) + tolowerRoman(n % 10);
    if (n < 60)
        return fill('x', 5 - n / 10) + 'l' + tolowerRoman(n % 10);
    if (n < 90)
        return std::string("l") + fill('x', n / 10 - 5) + tolowerRoman(n % 10);
    if (n < 110)
        return fill('x', 10 - n / 10) + "c" + tolowerRoman(n % 10);
    if (n < 400)
        return fill('c', n / 100) + tolowerRoman(n % 100);
    if (n < 600)
        return fill('c', 5 - n / 100) + 'd' + tolowerRoman(n % 100);
    if (n < 900)
        return std::string("d") + fill('c', n / 100 - 5) +
               tolowerRoman(n % 100);
    if (n < 1100)
        return fill('c', 10 - n / 100) + "m" + tolowerRoman(n % 100);
    if (n < 4000)
        return fill('m', n / 1000) + tolowerRoman(n % 1000);
    return "?";
}

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toupperRoman()

std::string toupperRoman

(

int

n

)

to convert to uppercase Roman Numeral the function works recursively

                              {
    if (n < 4)
        return fill('I', n);
    if (n < 6)
        return fill('I', 5 - n) + "V";
    if (n < 9)
        return std::string("V") + fill('I', n - 5);
    if (n < 11)
        return fill('I', 10 - n) + "X";
    if (n < 40)
        return fill('X', n / 10) + toupperRoman(n % 10);
    if (n < 60)
        return fill('X', 5 - n / 10) + 'L' + toupperRoman(n % 10);
    if (n < 90)
        return std::string("L") + fill('X', n / 10 - 5) + toupperRoman(n % 10);
    if (n < 110)
        return fill('X', 10 - n / 10) + "C" + toupperRoman(n % 10);
    if (n < 400)
        return fill('C', n / 100) + toupperRoman(n % 100);
    if (n < 600)
        return fill('C', 5 - n / 100) + 'D' + toupperRoman(n % 100);
    if (n < 900)
        return std::string("D") + fill('C', n / 100 - 5) +
               toupperRoman(n % 100);
    if (n < 1100)
        return fill('C', 10 - n / 100) + "M" + toupperRoman(n % 100);
    if (n < 4000)
        return fill('M', n / 1000) + toupperRoman(n % 1000);
    return "?";
}

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