To and from Strings - Rust By Example
Description: Rust by Example (RBE) is a collection of runnable examples that illustrate various Rust concepts and standard libraries.

# To and from Strings

## Converting to String

To convert any type to a `String` is as simple as implementing the `ToString` trait for the type. Rather than doing so directly, you should implement the `fmt::Display` trait which automagically provides `ToString` and also allows printing the type as discussed in the section on `print!`.

    use std::fmt;

    struct Circle {
        radius: i32
    }

    impl fmt::Display for Circle {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            write!(f, "Circle of radius {}", self.radius)
        }
    }

    fn main() {
        let circle = Circle { radius: 6 };
        println!("{}", circle.to_string());
    }

## Parsing a String

One of the more common types to convert a string into is a number. The idiomatic approach to this is to use the `parse` function and either to arrange for type inference or to specify the type to parse using the 'turbofish' syntax. Both alternatives are shown in the following example.

This will convert the string into the type specified so long as the `FromStr` trait is implemented for that type. This is implemented for numerous types within the standard library. To obtain this functionality on a user defined type simply implement the `FromStr` trait for that type.

    fn main() {
        let parsed: i32 = "5".parse().unwrap();
        let turbo_parsed = "10".parse::<i32>().unwrap();

        let sum = parsed + turbo_parsed;
        println!("Sum: {:?}", sum);
    }