64 bit enum in C++?

Question

Is there a way to have a 64 bit enum in C++? Whilst refactoring some code I came across bunch of #defines which would be better as an enum, but being greater than 32 bit causes the compiler to error.

For some reason I thought the following might work:

enum MY_ENUM : unsigned __int64  
{  
    LARGE_VALUE = 0x1000000000000000,  
};

Answer 1

I don't think that's possible with C++98. The underlying representation of enums is up to the compiler. In that case, you are better off using:

const __int64 LARGE_VALUE = 0x1000000000000000L;

As of C++11, it is possible to use enum classes to specify the base type of the enum:

enum class MY_ENUM : unsigned __int64 {
    LARGE_VALUE = 0x1000000000000000ULL
};

In addition enum classes introduce a new name scope. So instead of referring to LARGE_VALUE, you would reference MY_ENUM::LARGE_VALUE.

Answer 2

C++11 supports this, using this syntax:

enum class Enum2 : __int64 {Val1, Val2, val3};