Ownership and move in Rust

Every value has one owner; passing it moves it.

fn takes_ownership(s: String) -> usize {
    s.len()
}

fn main() {
    let text = String::from("hello");
    let n = takes_ownership(text);
    // `text` has moved into the function; only `n` remains

    let a = String::from("keep");
    let b = a.clone();
    println!("{n} {a} {b}");
}

How it works

1. Passing a String moves it into the function.
2. After a move the original binding is unusable.
3. clone makes an independent copy to keep both.

Keywords and builtins used here

• String
• fn
• let
• main
• takes_ownership
• usize

The run, in numbers

Lines

13

Characters to type

261

Tokens

71

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 47 seconds.

Type this snippet

Step 1 of 3 in Move & clone, step 1 of 15 in Ownership & borrowing.

Next →