Roman numerals to integers

Question

I have a transfer with products that unfortunately has to get matched by product name. The biggest issue here is I might get duplicate products on account of roman numbers.

Answer 1

I wrote a simple Roman Numeral Converter just now, but it doesn't do a whole lot of error checking, but it seems to work for everything I could throw at it that is properly formatted.

public class RomanNumber
{
    public string Numeral { get; set; }
    public int Value { get; set; }
    public int Hierarchy { get; set; }
}

public List RomanNumbers = new List
    {
        new RomanNumber {Numeral = "M", Value = 1000, Hierarchy = 4},
        //{"CM", 900},
        new RomanNumber {Numeral = "D", Value = 500, Hierarchy = 4},
        //{"CD", 400},
        new RomanNumber {Numeral = "C", Value = 100, Hierarchy = 3},
        //{"XC", 90},
        new RomanNumber {Numeral = "L", Value = 50, Hierarchy = 3},
        //{"XL", 40},
        new RomanNumber {Numeral = "X", Value = 10, Hierarchy = 2},
        //{"IX", 9},
        new RomanNumber {Numeral = "V", Value = 5, Hierarchy = 2},
        //{"IV", 4},
        new RomanNumber {Numeral = "I", Value = 1, Hierarchy = 1}
    };

/// 

/// Converts the roman numeral to int, assumption roman numeral is properly formatted.
/// 
/// The roman numeral string.
/// 
private int ConvertRomanNumeralToInt(string romanNumeralString)
{
    if (romanNumeralString == null) return int.MinValue;

    var total = 0;
    for (var i = 0; i < romanNumeralString.Length; i++)
    {
        // get current value
        var current = romanNumeralString[i].ToString();
        var curRomanNum = RomanNumbers.First(rn => rn.Numeral.ToUpper() == current.ToUpper());

        // last number just add the value and exit
        if (i + 1 == romanNumeralString.Length)
        {
            total += curRomanNum.Value;
            break;
        } 

        // check for exceptions IV, IX, XL, XC etc
        var next = romanNumeralString[i + 1].ToString();
        var nextRomanNum = RomanNumbers.First(rn => rn.Numeral.ToUpper() == next.ToUpper());

        // exception found
        if (curRomanNum.Hierarchy == (nextRomanNum.Hierarchy - 1))
        {
            total += nextRomanNum.Value - curRomanNum.Value;
            i++;
        }
        else
        {
            total += curRomanNum.Value;
        }
    }


    return total;
}