Borrowing Basics

Core idea

Rust separates ownership from borrowing so the compiler can prevent data races and dangling references before runtime.

Revision points

• One mutable reference or many immutable references.
• References cannot outlive the value they point to.
• Borrow checking pushes lifetime decisions earlier in design.

fn print_length(value: &String) {
    println!("{}", value.len());
}

fn main() {
    let name = String::from("notes");
    print_length(&name);
}

What to remember

When a Rust API feels strict, it is usually forcing you to clarify ownership boundaries.