Rust Programming Tutorials, Guides & Best Practices

Borrowing allows you to access a value without taking ownership. This is done through references, which come in two forms: immutable and mutable. Rust’s borrowing rules ensure that data races and other concurrency issues are avoided.

fn main() {
    let s = String::from("hello");
    let len = calculate_length(&s); // borrow s immutably
    println!("The length of '{}' is {}.", s, len); // s is still valid
}

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