how-to-create-enum-from-string-in-rust.md

How to create enum from string in Rust

// plain

Enums in Rust can be created from strings using the FromStr trait. This trait is implemented for the str type, allowing us to convert a string into an enum. To do this, we must first define the enum and implement the FromStr trait for it. Then, we can use the str::parse method to convert a string into the enum.

use std::str::FromStr;

#[derive(Debug)]
enum Color {
    Red,
    Green,
    Blue,
}

impl FromStr for Color {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "Red" => Ok(Color::Red),
            "Green" => Ok(Color::Green),
            "Blue" => Ok(Color::Blue),
            _ => Err(()),
        }
    }
}

fn main() {
    let color = "Green".parse::<Color>().unwrap();
    println!("{:?}", color);
}

Output example:

Green

Explanation

The FromStr trait is implemented for the str type, allowing us to convert a string into an enum. To do this, we must first define the enum and implement the FromStr trait for it. Then, we can use the str::parse method to convert a string into the enum. In the example above, we define an enum Color with three variants, and implement the FromStr trait for it. We then use the str::parse method to convert the string "Green" into the Color enum.

Helpful links

• Rust Documentation - FromStr
• Rust Documentation - str::parse
• Rust by Example - Enums

group: rust-enums