Lifetime - Idiomatic Rust Snippets

Lifetime in Rust

In Rust, lifetimes are a way of ensuring that references are valid for as long as they are needed and no longer. Lifetimes prevent dangling references, which can lead to undefined behavior.


fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
    if x.len() > y.len() {
        x
    } else {
        y
    }
}

fn main() {
    let string1 = String::from("long string is long");
    let string2 = "xyz";

    let result = longest(string1.as_str(), string2);
    println!("The longest string is {}", result);
}

The function longest takes two string slices with the same lifetime 'a and returns a string slice with the same lifetime 'a. This ensures that the returned reference is valid as long as both input references are valid.

Key Points

Lifetimes are denoted with an apostrophe followed by a name, like 'a.
They help the Rust compiler ensure that references do not outlive the data they point to.
Lifetimes are inferred by the compiler in many cases, but sometimes they need to be explicitly annotated.

For more detailed information, refer to the Rust Book.