Words To Numbers

This algorithm converts English words to decimal numbers.

• C#
• VB.Net
• C
• C++

									public static ulong WordsToNumbers(string words)
{
	if (string.IsNullOrEmpty(words)) return 0;
	
	words = words.Trim();
	words += ' ';

	ulong number = 0;
	string[] singles = new string[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };
	string[] teens = new string[] { "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
	string[] tens = new string[] { "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninty" };
	string[] powers = new string[] { "", "thousand", "million", "billion", "trillion", "quadrillion", "quintillion" };

	for (int i = powers.Length - 1; i >= 0; i--)
	{
		if (!string.IsNullOrEmpty(powers[i]))
		{
			int index = words.IndexOf(powers[i]);

			if (index >= 0 && words[index + powers[i].Length] == ' ')
			{
				ulong count = WordsToNumbers(words.Substring(0, index));
				number += count * (ulong)Math.Pow(1000, i);
				words = words.Remove(0, index);
			}
		}
	}

	{
		int index = words.IndexOf("hundred");

		if (index >= 0 && words[index + "hundred".Length] == ' ')
		{
			ulong count = WordsToNumbers(words.Substring(0, index));
			number += count * 100;
			words = words.Remove(0, index);
		}
	}

	for (int i = tens.Length - 1; i >= 0; i--)
	{
		if (!string.IsNullOrEmpty(tens[i]))
		{
			int index = words.IndexOf(tens[i]);

			if (index >= 0 && words[index + tens[i].Length] == ' ')
			{
				number += (uint)(i * 10);
				words = words.Remove(0, index);
			}
		}
	}

	for (int i = teens.Length - 1; i >= 0; i--)
	{
		if (!string.IsNullOrEmpty(teens[i]))
		{
			int index = words.IndexOf(teens[i]);

			if (index >= 0 && words[index + teens[i].Length] == ' ')
			{
				number += (uint)(i + 10);
				words = words.Remove(0, index);
			}
		}
	}

	for (int i = singles.Length - 1; i >= 0; i--)
	{
		if (!string.IsNullOrEmpty(singles[i]))
		{
			int index = words.IndexOf(singles[i] + ' ');

			if (index >= 0 && words[index + singles[i].Length] == ' ')
			{
				number += (uint)(i);
				words = words.Remove(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";
ulong value = WordsToNumbers(data);
								

Output

									5478775544879599