Can you use Enum for Double variables?

Question

I have created a class for handling Unit Conversion in C#. It is not working as it should only returning strings.

Here is the class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace RestaurantManagementSystem
{
    class unitHandler
    {
        public enum Units
        {
            Grams = 1,
            KiloGrams = 0.001,
            Milligram = 1000,
            Pounds = 0.00220462,
            Ounces = 0.035274,
            Tonnes = 0.000001,

            Litres = 1,
            Millilitres = 1000,
            Cups = 4.22675,
            FluidOunces = 33.814,
            TeaSpoon = 202.884,
            TableSpoon = 67.628,
            CubicFeet = 0.0353147,
            CubicInch = 61.0237,
            CubicCentimetres = 0.0001,
            CubicMetres = 0.001

        }

        public double Convert_Value(Units from, Units to, double quantity)
        {
            double converted_quantity = 0;

            double fromValue = quantity * Convert.ToDouble(from.ToString());

            converted_quantity = fromValue * Convert.ToDouble(to.ToString());

            return converted_quantity;
        }
    }
}

I would somehow want the enum type to contain the double values of conversion factors of each unit then use them for conversion and returning the converted quantity.

Answer 1

No, The default type for enum is int or long and you could not use fractional numbers with it. You can use a struct or class intead of enum for double

public struct Units
{
        public const double Grams = 1;
        public const double KiloGrams = 0.001;
        public const double Milligram = 1000;
        public const double Pounds = 0.00220462;
        public const double Ounces = 0.035274;
        public const double Tonnes = 0.000001;
        // Add Remaining units / values
}

And use it like

double d = Units.KiloGrams;

Answer 2

Nope:

I tried giving this to Visual Studio:

public enum Test : double
{
    Hello, World
}

And it said:

Type byte, sbyte, short, ushort, int, uint, long, or ulong expected

Answer 3

You can't use float/double with enums. You may have to define constants.

public const double KiloGrams = 0.001;