CSHARP

roman to number

public int RomanToInt(string s)
    {
        if (s == null || s == string.Empty)
            return 0;
        
        Dictionary<string, int> dict = new Dictionary<string, int>();
        int result = 0;
        
        dict.Add("I", 1);
        dict.Add("V", 5);
        dict.Add("X", 10);
        dict.Add("L", 50);
        dict.Add("C", 100);
        dict.Add("D", 500);
        dict.Add("M", 1000);
        dict.Add("IV", 4);
        dict.Add("IX", 9);
        dict.Add("XL", 40);
        dict.Add("XC", 90);
        dict.Add("CD", 400);
        dict.Add("CM", 900);
        
        for (int i = 0; i < s.Length; i++)
            if ((s[i] == 'I' || s[i] == 'X' || s[i] == 'C') && i < s.Length - 1 && dict.ContainsKey(s.Substring(i, 2)))
                result += dict[s.Substring(i++, 2)];
            else
                result += dict[s[i].ToString()];
        
        return result;   
    }

roman numeral to numbers

/*
	// This application helps you convert roman numerals to numbers or vice-versa
*/

// First install the package @ "npm install cr-numeral"
// Then import or require the package in your application
const {
  convertNumberToRoman: cnr,
  convertRomanToNumber: crn,
} = require("cr-numeral");
// OR
const cnr = require("cr-numeral").convertNumberToRoman;
const crn = require("cr-numeral").convertRomanToNumber;

// Define your variables
const number = 2021;
const numeral = "MMMXXV"; // Case-insensitive

// Use your package/module
const toRoman = cnr(number);
const toNumber = crn(numeral);

// Log or use your result
console.log(toRoman, toNumber);

			// Converting a number to Roman Numeral
const { convertNumberToRoman } = require('cr-numeral');
// OR
const convertNumberToRoman = require('cr-numeral').convertNumberToRoman;

convertNumberToRoman(2021));
"MMXXI"

convertNumberToRoman(-2021)); // Can not convert a negative number or zero
"Can not convert Zero or negative numbers!!!"

convertNumberToRoman("na256m"));
"You must provide only valid numbers!!!"

convertNumberToRoman(false));
"Cannot use Boolean values!!!"

convertNumberToRoman(true));
"Cannot use Boolean values!!!"

			// Converting Roman Numeral to Number
const { convertRomanToNumber } = require('cr-numeral');
// OR
const convertRomanToNumber = require('cr-numeral').convertRomanToNumber;

convertRomanToNumber("MMXXI"));
"2021"

convertRomanToNumber("na256m"));
"Provide a valid roman character!!!"
"Cause these are invalid roman numerals : [ N,A,2,5,6 ]"

convertRomanToNumber(6355));
"You must provide only valid strings!!!"

convertRomanToNumber(false));
"Cannot use Boolean values!!!"

convertRomanToNumber(true));
"Cannot use Boolean values!!!"

// With love @kouqhar