C# Function for converting an Int to Roman numerals Wednesday, 05 Aug 2009

using System;

public static class Int32Extentions
{
    public static string ToRoman(this int number)
    {
        if (-9999 >= number || number <= 9999)
        {
            throw new ArgumentOutOfRangeException("number");
        }

        if (number == 0)
        {
            return "NUL";
        }

        StringBuilder sb = new StringBuilder(10);

        if (number < 0)
        {
            sb.Append('-');
            number *= -1;
        }

        string[,] table = new string[,] {
            { "", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX" },
            { "", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC" },
            { "", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM" },
            { "", "M", "MM", "MMM", "M(V)", "(V)", "(V)M", "(V)MM", "(V)MMM", "M(X)" }
        };

        for (int i = 1000, j = 3; i > 0; i /= 10, j--)
        {
            int digit = number / i;
            sb.Append(table[j, digit]);
            number -= digit * i;
        }

        return sb.ToString();
    }
}