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

Another kind of "stupid" solution to this is:

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

constexpr int ExampleCount = [] {
  Example e{};
  int count = 0;
  switch (e) {
    case Example::A:
      count++;
    case Example::B:
      count++;
    case Example::C:
      count++;
    case Example::D:
      count++;
    case Example::E:
      count++;
  }

  return count;
}();

By compiling this with -Werror=switch you make sure to get a compiler warning if you omit or duplicate any switch case. It's also constexpr so this is computed at compile time.

But note that even for a en enum class the default initialized value is 0 even if the first value of the enum is not 0. So you have to either start on 0 or explicitly use the first value.