Words To Numbers

This algorithm converts English words to decimal numbers.

• C#
• VB.Net
• C
• C++

									/*****Please include following header files*****/
// string
// vector
/***********************************************/

/*****Please use following namespaces*****/
// std
/*****************************************/

static inline string RTrim(const string& s, const string& delimiters = " \f\n\r\t\v") {
	return s.substr(0, s.find_last_not_of(delimiters) + 1);
}

static inline string LTrim(const string& s, const string& delimiters = " \f\n\r\t\v") {
	return s.substr(s.find_first_not_of(delimiters));
}

static inline string Trim(const string& s, const string& delimiters = " \f\n\r\t\v") {
	return LTrim(RTrim(s, delimiters), delimiters);
}

static uint64_t WordsToNumbers(string words) {
	if (words.empty()) return 0;
	words = Trim(words);
	words += ' ';

	uint64_t number = 0;
	vector<string> singles = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };
	vector<string> teens = { "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
	vector<string> tens = { "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninty" };
	vector<string> powers = { "", "thousand", "million", "billion", "trillion", "quadrillion", "quintillion" };
	int singlesLength = singles.size();
	int teensLength = teens.size();
	int tensLength = tens.size();
	int powersLength = powers.size();

	for (int i = powersLength - 1; i >= 0; i--)
	{
		if (!(powers[i].empty()))
		{
			int index = words.find(powers[i], 0);

			if (index >= 0 && words[index + powers[i].length()] == ' ')
			{
				uint64_t count = WordsToNumbers(words.substr(0, index));
				number += count * (uint64_t)pow(1000, i);
				words = words.erase(0, index);
			}
		}
	}

	{
		int index = words.find("hundred", 0);

		if (index >= 0 && words[index + string("hundred").length()] == ' ')
		{
			uint64_t count = WordsToNumbers(words.substr(0, index));
			number += count * 100;
			words = words.erase(0, index);
		}
	}

	for (int i = tensLength - 1; i >= 0; i--)
	{
		if (!(tens[i].empty()))
		{
			int index = words.find(tens[i], 0);

			if (index >= 0 && words[index + tens[i].length()] == ' ')
			{
				number += (unsigned int)(i * 10);
				words = words.erase(0, index);
			}
		}
	}

	for (int i = teensLength - 1; i >= 0; i--)
	{
		if (!(teens[i].empty()))
		{
			int index = words.find(teens[i], 0);

			if (index >= 0 && words[index + teens[i].length()] == ' ')
			{
				number += (unsigned int)(i + 10);
				words = words.erase(0, index);
			}
		}
	}

	for (int i = singlesLength - 1; i >= 0; i--)
	{
		if (!(singles[i].empty()))
		{
			int index = words.find(singles[i] + ' ', 0);

			if (index >= 0 && words[index + singles[i].length()] == ' ')
			{
				number += (unsigned int)(i);
				words = words.erase(0, index);
			}
		}
	}

	return number;
}
								

Example

									string data = "five quadrillion four hundred seventy eight trillion seven hundred seventy five billion five hundred forty four million eight hundred seventy nine thousand five hundred ninty nine";
uint64_t value = WordsToNumbers(data);
								

Output

									5478775544879599