Flag enums

I was working on a project that needed to use flag enums to store state.  Flag enums are great, except after 2^15 the numbers get hard to calculate. I resorted to using excel to generate the enum code for me, that is until I learned I can do math expressions inside of enums! What I forgot is that 2^0 is not equivalent to Math.Pow(2,0).  This is when I discovered my old friend shift.

 

 

using System;

namespace TestEnum
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(oldway.All);
            Console.WriteLine(newway.All);
        }
    }

    [Flags]
    enum oldway
    {
        None=0,
        One=1,
        Two=2,
        Three=4,
        Four=8,
        All=15
    }

    [Flags]
    enum newway
    {
        None = 0,
        One = 1<<0,
        Two = 1<<1,
        Three = 1<<2,
        Four = 1<<3,
        All = (1<<4) - 1
    }
}

 

As you can see they both work the same :)