iterate through non-consecutive enum elements in c++

Question

There are many ways to iterate through consecutive enums like

enum Animal {Cat, Dog, Dolphin}

But is there a convenient and easy way to iterate through non-consecutive enum elements like

enum Animal {Cat = 0, Dog = 5, Dolphin = 8}

Answer 1

The short answer to this is "no".

You could make a table animals, and then use a range loop on animals.

Here's a complete "demo":

#include <iostream>

using namespace std;

enum Animal {Cat = 0, Dog = 5, Dolphin = 8};

int main()
{
    Animal animals[] = { Cat, Dog, Dolphin };

    for(Animal a : animals) cout << a << endl;
}

The output will be:

0
5
8

Answer 2

You could also provide the necessary operator(s) for the enumeration:

enum Animal
{
  Cat = 0
  , Dog = 5
  , Dolphin = 8
};

inline Animal& operator++ (Animal &x)
{
  switch (x) {
    case Cat:
      x = Dog;
      break;
    case Dog:
      x = Dolphin;
      break;
    case Dolphin:
    default:
      x = static_cast<Animal>(static_cast<int>(x) + 1);
      break;
  }
  return x;
}

DTTO for postfix ++, < and anything else you need. Of course, you have to keep them in sync with the definition of the enumeration. Not really straightforward, but it is an option.