c# - Convert a text fraction to a decimal

Question

Similar to this question just in C# instead of JavaScript. I couldn't find anything for C# while searching

I have a text box that will take a quantity, which is later stored as a double in a database. However it is possible that some quantities will be entered as string fractions e.g 1/2 for 0.5. I want to be able to convert these to decimal before storing them to the database (being able to also convert back would be nice but not necessary). I want to be able to handle both fractions and mixed numbers e.g. 2 1/2 is saved as 2.5

Anybody know a way of doing this?

Answer 1

Try splitting it on the space and slash, something like:

double FractionToDouble(string fraction) {
    double result;

    if(double.TryParse(fraction, out result)) {
        return result;
    }

    string[] split = fraction.Split(new char[] { ' ', '/' });

    if(split.Length == 2 || split.Length == 3) {
        int a, b;

        if(int.TryParse(split[0], out a) && int.TryParse(split[1], out b)) {
            if(split.Length == 2) {
                return (double)a / b;
            }

            int c;

            if(int.TryParse(split[2], out c)) {
                return a + (double)b / c;
            }
        }
    }

    throw new FormatException("Not a valid fraction.");
}

Hey, it worked! Remember to check for a division by zero, too. You'll get Infinity, -Infinity, or NaN as a result.