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Enums in Rust Programing
Also referred to as enumerations, enums are very useful in certain cases. In Rust, we use enums, as they allow us to define a type that may be one of a few different variants.
Enumerations are declared with the keyword enum.
Example
#![allow(unused)]
#[derive(Debug)]
enum Animal {
Dog,
Cat,
}
fn main() {
let mut b : Animal = Animal::Dog;
b = Animal::Cat;
println!("{:?}",b);
}Output
Cat
Zero-variant Enums
Enums in Rust can also have zero variants, hence the name Zero-variant enums. Since they do not have any valid values, they cannot be instantiated.
Zero-variant enums are equivalent to the never type in Rust.
Example
#![allow(unused)]
#[derive(Debug)]
enum ZeroVariantEnum {}
fn main() {
let x: ZeroVariantEnum = panic!();
println!("{:?}",x);
}Output
thread 'main' panicked at 'explicit panic', src/main.rs:7:30
Updated on: 03-Apr-2021
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