C#: Convert a given Roman numerals value to an integer value

C# Sharp Math: Exercise-15 with Solution

Write a C# Sharp program to convert a given Roman numeral value to an integer value.

From Wikipedia,
Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers in this system are represented by combinations of letters from the Latin alphabet. Modern usage employs seven symbols, each with a fixed integer value.

Symbol	I	V	X	L	C	D	M
Value      1	5	10	50	100	500	1000

Sample Solution:

C# Sharp Code:

using System;
using System.Text;
namespace exercises {
  class Program {
    static void Main(string[] args) {
      string s;
      s = "MMCCCLXV";
      Console.WriteLine("Original integer value: " +s);
      Console.WriteLine("Integer value of the said Roman numerals:");
      Console.WriteLine(roman_to_int(s));
      s = "CCLIV";
      Console.WriteLine("Original integer value: " + s);
      Console.WriteLine("Integer value of the said Roman numerals:");
      Console.WriteLine(roman_to_int(s));
      s = "XLV";
      Console.WriteLine("Original integer value: " + s);
      Console.WriteLine("Integer value of the said Roman numerals:");
      Console.WriteLine(roman_to_int(s));
      s = "VIII";
      Console.WriteLine("Original integer value: " + s);
      Console.WriteLine("Integer value of the said Roman numerals:");
      Console.WriteLine(roman_to_int(s));	  
      }


    public static int roman_to_int(string str1)
        {
            var num = 0;
            for (int i = 0; i < str1.Length; i++)
            {
                if (i > 0 && find_value(str1[i]) > find_value(str1[i - 1]))
                {
                    num += find_value(str1[i]) - find_value(str1[i - 1]) * 2;
                }
                else
                {
                    num += find_value(str1[i]);
                }
            }

            return num;
        }
		
	   public static int find_value(char chr)
        {
            switch (chr)
            {
                case 'I': return 1;
                case 'V': return 5;
                case 'X': return 10;
                case 'L': return 50;
                case 'C': return 100;
                case 'D': return 500;
                case 'M': return 1000;
                default: return 0;
            }
        }	
    }
  }

Sample Output:

Original integer value: MMCCCLXV
Integer value of the said Roman numerals:
2365
Original integer value: CCLIV
Integer value of the said Roman numerals:
254
Original integer value: XLV
Integer value of the said Roman numerals:
45
Original integer value: VIII
Integer value of the said Roman numerals:
8

Flowchart:

C# Sharp Code Editor:

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