Convert numbers in string to English word format

debugcn Published at Dev

Zach

I have a C# method that converts integer numbers into their English word counterparts; however, how can I implement this so it'll work with a string.

For example, if I have the following string:

There was a dog. The dog ate 1000 bones. After eating, he was very sleepy. He slept for 12 hours.

I want it to parse it and return:

There was a dog. The dog ate one thousand bones. After eating, he was very sleepy. He slept for twelve hours.

How would I go by taking the numbers out of the sentence, and using the conversion method (below)?

public static string NumberToWords(int number)
{
    if (number == 0)
        return "zero";

    if (number < 0)
        return "minus " + NumberToWords(Math.Abs(number));

    string words = "";

    if ((number / 1000000) > 0)
    {
        words += NumberToWords(number / 1000000) + " million ";
        number %= 1000000;
    }

    if ((number / 1000) > 0)
    {
        words += NumberToWords(number / 1000) + " thousand ";
        number %= 1000;
    }

    if ((number / 100) > 0)
    {
        words += NumberToWords(number / 100) + " hundred ";
        number %= 100;
    }

    if (number > 0)
    {
        if (words != "")
            words += "and ";

        var unitsMap = new[] { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
        var tensMap = new[] { "zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" };

        if (number < 20)
            words += unitsMap[number];
        else
        {
            words += tensMap[number / 10];
            if ((number % 10) > 0)
                words += "-" + unitsMap[number % 10];
        }
    }

    return words;
}

I tried doing a foreach, like this, but it didn't work...

var matches = Regex.Matches(myString, "[0-9]+");
foreach(var match in matches)
{
   NumberToWords(match);
}

Selman Genç

You could use Split and LINQ:

var input = "There was a dog. The dog ate 1000 bones. After eating, he was very sleepy. He slept for 12 hours.";

var invalidChars = new [] { ',', ';', '-', '.' };
var words = input.Split(' ')
            .Select(x =>
            {
                if (x.All(char.IsDigit) || x.Trim(invalidChars).All(char.IsDigit))
                    return NumberToWords(int.Parse(x.Trim(invalidChars)));
                return x;
            });

var output = string.Join(" ", words);

Btw I assume that NumberToWord method is working correctly.

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