Roman To Numbers

This algorithm converts roman numerals to decimal numbers.

• C#
• VB.Net
• C
• C++
• PHP

									/*****Please include following header files*****/
// stdint.h
/***********************************************/

void RTrim(char* str) {
	size_t n;
	n = strlen(str);

	while (n > 0 && isspace((unsigned char)str[n - 1])) {
		n--;
	}

	str[n] = '\0';
}

void LTrim(char* str) {
	size_t n;
	n = 0;

	while (str[n] != '\0' && isspace((unsigned char)str[n])) {
		n++;
	}

	memmove(str, str + n, strlen(str) - n + 1);
}

void Trim(char* str) {
	RTrim(str);
	LTrim(str);
}

int RomanToNumber(char romanChar) {
	switch (romanChar)
	{
	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:
		break;
	}

	return 0;
}

int RomanToNumbers(char* roman) {
	roman = _strupr(roman);
	Trim(roman);
	if (roman == "N") return 0;

	int ptr = 0;
	int total = 0;
	int valuesCount = 0;
	int maxDigit = 1000;
	int romanLen = strlen(roman);

	while (ptr < romanLen)
	{
		char numeral = roman[ptr];
		int digit = RomanToNumber(numeral);

		int nextDigit = 0;
		if (ptr < romanLen - 1)
		{
			char nextNumeral = roman[ptr + 1];
			nextDigit = RomanToNumber(nextNumeral);

			if (nextDigit > digit)
			{
				maxDigit = digit - 1;
				digit = nextDigit - digit;
				ptr++;
			}
		}

		total += digit;
		ptr++;
	}

	return total;
}
								

Example

									char data[] = "CDXIX";
int value = RomanToNumbers(data);
								

Output

									419