Enumerator value evaluates to 2147483648, which cannot be narrowed to type 'int'-CodePudding

I created an enum like this:

enum class CATEGORIES{
       C01 = 0x00000001,
       C02 = 0x00000002,
       C03  = 0x00000004,
       ...
       C26 = 0x02000000,
       C27 = 0x04000000,
       C28 = 0x08000000,
       C29 = 0x10000000,
       C30 = 0x20000000,
       C31 = 0x40000000,
       C32 = 0x80000000, //Error at this line
    }

Enumerator value evaluates to 2147483648, which cannot be narrowed to type 'int'

How should I resolve it? I just wanted a convenient way of representing the categories, and enum class seemed to make sense for namespacing..

CodePudding user response：

Someone suggested the following and then deleted their comment, but it seemed to work, making the underlying type unsigned int:

enum class CATEGORIES : uint32_t{
 ...
}

CodePudding user response：

0x80000000 is 2147483648 in base 10, and an int cannot contain 2147483648

You should do this:

enum class CATEGORIES : unsigned long{
       C01 = 0x00000001,
       C02 = 0x00000002,
       C03 = 0x00000004,
       ...
       C26 = 0x02000000,
       C27 = 0x04000000,
       C28 = 0x08000000,
       C29 = 0x10000000,
       C30 = 0x20000000,
       C31 = 0x40000000,
       C32 = 0x80000000,
}; // also you seem to miss this semicolon

CodePudding user response：

Without specifying explicitly the underlying type of CATEGORIES is int, and 0x80000000 (2147483648) is outside of the range of int on your platform.

You can specify a larger type (e.g. long; depending on your needs) as the underlying type explicitly.

enum class CATEGORIES : long {
   C01 = 0x00000001,
   C02 = 0x00000002,
   C03  = 0x00000004,
   ...
   C26 = 0x02000000,
   C27 = 0x04000000,
   C28 = 0x08000000,
   C29 = 0x10000000,
   C30 = 0x20000000,
   C31 = 0x40000000,
   C32 = 0x80000000,
};