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,
...

Answer 3

I'd be tempted to consider using BitArray as the underlying structure.