private int findRomanSpecialNumber(romanDigit character)
{
double conditionNumber = (int)character;
while (conditionNumber > 10)
{
conditionNumber *= 0.1;
}
return((conditionNumber % 2 == 0) ? (int)((int)character * 0.9) : (int)((int)character - ((int)character * 0.2)));
}
/// <summary>
/// Converts a roman numeral into an arabic number.
/// </summary>
/// <param name="num">A roman numeral.</param>
/// <returns>AN arabic number.</returns>
public int ConvertRomanToArabic(string num)
{
if (num == null)
{
return(0);
}
int i = 0, value = 0;
var numberString = num.ToUpper().Trim();
int amountOfChars = numberString.Length;
var romanCharacters = Enum.GetValues(typeof(romanDigit));
int currentRomanDigit = romanCharacters.Length;
romanDigit character = (romanDigit)romanCharacters.GetValue(--currentRomanDigit);
// A Guardian instance checks if a romanDigit in the roman numeral appears maximum three times,
// otherwise it throws an exception.
Guardian guardian = new Guardian(3, () => { throw new Exception("Your number format is wrong."); });
do
{
if (character.ToString() == numberString[i].ToString())
{
guardian.Call();
value += (int)character;
i++;
}
else
{
if ((amountOfChars - i) > 1)
{
int specialSymbol = findRomanSpecialNumber(character);
romanSpecialNumber rsn = (Enum.GetValues(typeof(romanSpecialNumber))).OfType <romanSpecialNumber>().ToList().Find(x => (int)x == specialSymbol);
if (numberString.Substring(i, 2) == rsn.ToString())
{
value += (int)rsn;
i += 2;
}
}
if (currentRomanDigit == 0)
{
throw new Exception("You gave a wrong sign in your roman number or one of the " +
"digits is on a wrong position");
}
character = (romanDigit)romanCharacters.GetValue(--currentRomanDigit);
guardian.ResetNumberOfCalls();
}
}while (amountOfChars > i);
return(value);
}
/// <summary>
/// Converts an arabic number into a roman numeral.
/// A number to convert must be in the range of 0 to 3999.
/// </summary>
/// <param name="num">An arabic number to convert.</param>
/// <returns>A roman numeral.</returns>
public string ConvertArabicToRoman(int num)
{
if (num > 3999 || num <= 0)
{
return(null);
}
int number = num;
StringBuilder value = new StringBuilder();
var romanCharacters = Enum.GetValues(typeof(romanDigit));
int i = romanCharacters.GetLength(0) - 1;
romanDigit character = (romanDigit)romanCharacters.GetValue(i);
do
{
if (number >= (int)character)
{
value.Append(character);
number = number - (int)character;
}
else
{
if (character != romanDigit.I)
{
int specialSymbol = findRomanSpecialNumber(character);
if (specialSymbol <= number)
{
romanSpecialNumber rsn = (Enum.GetValues(typeof(romanSpecialNumber))).OfType <romanSpecialNumber>().ToList().Find(x => (int)x == specialSymbol);
value.Append(rsn);
number -= (int)rsn;
}
}
character = (romanDigit)romanCharacters.GetValue(--i);
}
}while (number > 0);
return(value.ToString());
}