How is it that an enum derives from System.Enum and is an integer at the same time?

Question

Edit: Comments at bottom. Also, this.

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Here\'s what\'s kind of confusing me. My understanding is that if I have an enum like this...

Answer 1

A Enum's underlying type is the type used to store the value of the constants. In your example, even though you haven't explicitly defined the values, C# does this:

enum Animal : int
{
    Dog = 0,
    Cat = 1
}

Internally, Animal is made up of two constants with the integer values 0 and 1. That's why you can explicitly cast an integer to an Animal and an Animal to an integer. If you pass Animal.Dog to a parameter that accepts an Animal, what you are really doing is passing the 32bit integer value of Animal.Dog (in this case, 0). If you give Animal a new underlying type, then the values are stored as that type.