Slices and Lifetimes

Slices let you reference parts of a collection without taking ownership.

String Slice Example

let s = String::from("hello world");
let hello = &s[0..5];
let world = &s[6..11];

They point to a segment of memory.

Lifetimes

Lifetimes ensure references are valid while used.

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

'a is a lifetime annotation ensuring both parameters live long enough for the returned reference to be valid.