Rust - Control Flow: Loops

Control Flow: Loops

Rust has three kinds of loops: loop, while, for.

loop

The loop keyword creates an infinite loop.

    loop {
        println!("again!");
    }

You might also need to pass the result of that operation out of the loop to the rest of your code. To do this, you can add the value you want returned after the break expression you use to stop the loop

    let result = loop {
        counter += 1;

        if counter == 10 {
            break counter * 2;
        }
    };

Multiple Loops

You can optionally specify a loop label on a loop that you can then use with break or continue

    '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;
    }

while

Conditional Loop, a combination of loop, if, else, break

    while number != 0 {
        println!("{number}!");

        number -= 1;
    }

for

Looping Through a Collection

    for element in a {
        println!("the value is: {element}");
    }

Instead of using a while index < array_size. Increases the safety of the code and eliminated the chance of bugs that might result from going beyond the end of the array

We can also use to run some code a certain number of times

    // countdown
    for number in (1..4).rev() {
        println!("{number}!");
    }

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