How to Use Labeled Loops and break with Values in Rust

Use a label (e.g., 'outer) before a loop to target it with break, and append a value to break to return it from the loop block.

fn main() {
    let mut count = 0;
    'counting_up: loop {
        println!("count = {count}");
        let mut remaining = 10;

        loop {
            println!("remaining = {remaining}");
            if remaining == 9 {
                break;
            }
            if count == 2 {
                break 'counting_up;
            }
            remaining -= 1;
        }
        count += 1;
    }

    let result = loop {
        count += 1;
        if count == 10 {
            break count * 2;
        }
    };
    println!("The result is {result}");
}

Labels act like named anchors for loops, letting you break out of a specific nested loop instead of just the innermost one. You can also attach a value to the break command, which becomes the result of the entire loop block. Think of it like a labeled exit door in a maze that leads directly to a specific prize.