UENUM enum class with 256 values?

Development Programming & Scripting C++
1

Hey,

It seems like it is impossible to have a enum class with 256 values in it (or even one value that is 255)


UENUM()
enum class EByte : uint8 {
  Mask = 255,
};

generates a error stating that EByte_Max cannot be automatically defined as 256 because it wraps to zero over 8 bits and that I should manually define it in the enum so…


UENUM()
enum class EByte : uint8 {
  Mask = 255,
  EByte_Max = 255,
};

generates an error stating that manually defined values must be greater than previously entered ones…

right now my hacky fix for this is below


#if CPP
#define EByte_Max Mask
#endif
UENUM()
enum class EByte : uint8 {
  EByte_Max= 255,
};
#if CPP
#undef EByte_Max
#endif

The above hack gets UHT to stop complaining when there are actually 256 values in the enum, and EByte::Mask exists still. The problem is that Mask does not show up as an option if the enum is a UPROPERTY (neither does EByte_Max, even if UMETA(DisplayName=“Mask”) is used afterwards.

So I was curious if I perhaps am doing something wrong or if when using enum class your really only limited to 255 values, 0…254?

2

Did you try using uint or uint32 istead of uint8 ? Does it compile that way?

3

Thanks for the reply,

I got an error stating that UENUM on “enum class” type can only be of uint8. I would need it to be 8 bits either way though

4

You’re not doing anything wrong. UENUMs silently insert an additional member after the last one, a sort of sentinel value used for reflection I assume. So if “slot 255” is already occupied, UHT will complain about it.

5

Well that’s painful, but thanks for the response! Would be nice if they could fix it. Seems like they could just treat E…_MAX == 0 special, since your not allowed to have any enum types that are not unsigned 8 bit integers internally and your also not allowed to UENUM an enum with no entries in it.