How do I get the integer value of an enum?

Question

It is possible to write constructions like this:

enum Number {
    One = 1,
    Two = 2,
    Three = 3,
    Four = 4,
}

but for what purpos

Answer 1

You get the value by casting the enum variant to an integral type:

enum Thing {
    A = 1,
    B = 2,
}

fn main() {
    println!("{}", Thing::A as u8);
    println!("{}", Thing::B as u8);
}