Enum flags over 2^32

Question

I am using Enum flags in my application. The Enum can have around 50+ values, so values go up to 2^50. I was just wondering, can I use Math.Pow(2, variable) to calculate these?

When I try to do that I get a constant value compile-time error. Is there another way, other than calculating these powers of 2 manually and putting it in?

Here's what I am doing:

[Flags] internal enum RiskStates : long     {         None = 0,         AL = Convert.ToInt64(Math.Pow(2,0)),         AK = 2,         AZ = 4,         AR = 8,         CA = 16,         CO = 32,         CT = 64,         DC = 128,         DE = 256,         FL = 512,         GA = 1024,         HI = 2048,         ID = 4096,         IL = 8192,         IN = 16384,         IA = 32768,         KS = 65536,         KY = 131072,         LA = 262144,         ME = 524288,         MD = 1048576,         MA = 2097152,         MI = 4194304 } 

Answer 1

When I try to do that I get a constant value compile-time error.

You'd actually be okay if you used the L suffix to force it to be a long literal - but it's still not ideal to have to specify them all manually. (It's not "obviously correct" when reading the code.)

You can't use Math.Pow as the expression has to be a compile-time constant - but you can use bit-shifting:

None = 0, AL = 1L << 0, AK = 1L << 1, AZ = 1L << 2 

etc. I'd argue that's more readable anyway :)

Answer 2

If you change to using non-decimal notations where the powers of 2 are more regular then you will no longer need to generate them automatically, e.g.:

// octal AL = 0001L, AK = 0002L, AZ = 0004L, AR = 0010L, CA = 0020L, CO = 0040L, CT = 0100L, ...  // hexadecimal AL = 0x001L, AK = 0x002L, AZ = 0x004L, AR = 0x008L, CA = 0x010L, CO = 0x020L, CT = 0x040L, ...