Number of elements in an enum

In C, is there a nice way to track the number of elements in an enum? I've seen

enum blah {
    FIRST,
    SECOND,
    THIRD,
    LAST
};

But this only works if the items are sequential and start at zero.

If you don't assign your enums you can do somethings like this:

enum MyType {
  Type1,
  Type2,
  Type3,
  NumberOfTypes
}

NumberOfTypes will evaluate to 3 which is the number of real types.

I don't believe there is. But what would you do with such a number if they are not sequential, and you don't already have a list of them somewhere? And if they are sequential but start at a different number, you could always do:

enum blah {
    FIRST = 128,
    SECOND,
    THIRD,
    END
};
const int blah_count = END - FIRST;

Old question, I know. This is for the googlers with the same question.

You could use X-Macros

Example:

//The values are defined via a map which calls a given macro which is defined later
#define ENUM_MAP(X) \
      X(VALA, 0)    \
      X(VALB, 10)   \
      X(VALC, 20)

//Using the map for the enum decl
#define X(n, v) [n] = v,
typedef enum val_list {
    ENUM_MAP(X) //results in [VALA] = 0, etc...
} val_list;
#undef X

//For the count of values
#define X(n, v) + 1
int val_list_count = 0 + ENUM_MAP(X); //evaluates to 0 + 1 + 1 + 1
#undef X

This is also transparent to an IDE, so auto-completes will work fine (as its all done in the pre-processor).

Number of elements in an enum

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