Is it possible to determine the number of elements of a c++ enum class?

Question

Is it possible to determine the cardinality of a c++ enum class:

enum class Example { A, B, C, D, E };

I tried to use si

Answer 1

There is another way that doesn’t rely on line counts or templates. The only requirement is sticking the enum values in their own file and making the preprocessor/compiler do the count like so:

my_enum_inc.h

ENUMVAL(BANANA)
ENUMVAL(ORANGE=10)
ENUMVAL(KIWI)
...
#undef ENUMVAL

my_enum.h

typedef enum {
  #define ENUMVAL(TYPE) TYPE,
  #include "my_enum_inc.h"
} Fruits;

#define ENUMVAL(TYPE) +1
const size_t num_fruits =
  #include "my_enum_inc.h"
  ;

This allows you to put comments with the enum values, re-assign values and does not inject an invalid 'count' enum value that needs to be ignored/accounted for in code.

If you don't care about comments you don't need an extra file and can do as someone above mentioned, e.g.:

#define MY_ENUM_LIST \
    ENUMVAL(BANANA) \
    ENUMVAL(ORANGE = 7) \
    ENUMVAL(KIWI)

and replace the #include "my_enum_inc.h" directives with MY_ENUM_LIST but you'll need to #undef ENUMVAL after each use.