Table of Contents📚

• What is an enum type❓
• Declaring an enum type
• Matching on an enum
  • What is a match expression❓
  • Usage
  • Matching on an enum

Enum types

What is an enum type❓

Enums are a way to express your code in a descriptive and simple way.

They are a way to group related values together.

Declaring an enum type

An enum can be declared with the enum keyword, followed by the name of the enum, and then a list of variants.

ℹ️ The enums have to be declared out of the main function.

Example:

enum Animal {
    Monkey,
    Dog,
    Unicorn,
}

fn main() {
    ///
}

ℹ️ The enum and variants name are conventionally capitalized.

We can now use the enum to create a variable of type Animal.

let animal:Animal = Animal::Monkey;

ℹ️ We can use the :: operator to specify the variant of the enum (Monkey in this case).

Matching on an enum

What is a match expression❓

The match keyword is used to do different thingd based on the value of a variable.

ℹ️ It is similar to switch statements in other languages.

Usage

match variable {
    value => {
        // Do something
    }
    value2 => {
        // Do something else
    }
    _ => {
        // Do something else
    }
}

ℹ️ We can ignore the {} if wa expect only one line of code.

ℹ️ The _ is a catch all case that is used when no other cases match.

Matching on an enum

We can use the match keyword to match on an enum.

match animal {
    Animal::Monkey => println!("🐒"),
    Animal::Dog => println!("🐶"),
    Animal::Unicorn => println!("🦄"),
    _ => println!("🤖"),
}

value	Output
Animal::Monkey	🐒
Animal::Dog	🐶
Animal::Unicorn	🦄
Other	🤖

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