Question

I have a C# app and I need to convert between 3 different units (say for example: litres, gallons, and pints).

The app needs to know about certain volumes of liquid, say: 1 pint, 10 pints, 20 pints and 100 pints. I intend to do the calculations and hard code the values (not ideal but necessary),

I’m looking for a data structure that will allow me to easily convert from one unit to another.

Any suggestions?

Please note: I’m not actually using volumes of liquid, its just an example!

Answer 1

You can store a matrix of conversion factors where

• a: Is litres
• b: Is pints
• c: Are gallons

You’d have (not accurate, but assuming there are two pints to a litre and 4 litres to a gallon)

   a     b       c a  1     2     0.25 b  0.5   1     0.125 c  4     8       1 

Alternatively, you can decide that everything is converted to a base value (litres) before being converted to another type, then you just need the first line.

Wrap this in a method that takes a number of units and ‘from’ type and ‘two’ type for the conversion.

Hope this helps

EDIT: some code, as requested

    public enum VolumeType     {         Litre = 0,         Pint = 1,         Gallon = 2     }      public static double ConvertUnits(int units, VolumeType from, VolumeType to)     {         double[][] factor =              {                 new double[] {1, 2, 0.25},                 new double[] {0.5, 1, 0.125},                 new double[] {4, 8, 1}             };         return units * factor[(int)from][(int)to];     }      public static void ShowConversion(int oldUnits, VolumeType from, VolumeType to)     {         double newUnits = ConvertUnits(oldUnits, from, to);         Console.WriteLine('{0} {1} = {2} {3}', oldUnits, from.ToString(), newUnits, to.ToString());     }       static void Main(string[] args)     {         ShowConversion(1, VolumeType.Litre, VolumeType.Litre);  // = 1         ShowConversion(1, VolumeType.Litre, VolumeType.Pint);   // = 2         ShowConversion(1, VolumeType.Litre, VolumeType.Gallon); // = 4         ShowConversion(1, VolumeType.Pint, VolumeType.Pint);    // = 1         ShowConversion(1, VolumeType.Pint, VolumeType.Litre);   // = 0.5         ShowConversion(1, VolumeType.Pint, VolumeType.Gallon);  // = 0.125         ShowConversion(1, VolumeType.Gallon, VolumeType.Gallon);// = 1         ShowConversion(1, VolumeType.Gallon, VolumeType.Pint);  // = 8         ShowConversion(1, VolumeType.Gallon, VolumeType.Litre); // = 4         ShowConversion(10, VolumeType.Litre, VolumeType.Pint);  // = 20         ShowConversion(20, VolumeType.Gallon, VolumeType.Pint); // = 160     }