Such as enum{a, b, c}. The corresponding values of a, b and c are 0, 1, 2.
Of course, it can also be initialized, such as enum{a=3, b, c, d=7, e}. The corresponding values of a, b, c, d and e are 3, 4, 5, 7 and 8 respectively. (Note: Values cannot be duplicated! )
Since it is not a variable, of course, you can't put a pointer variable ~
It should be noted that you can write casually with curly braces, but you can't use integers!