Loops & Iterators

🦀 Rust Lesson 7 Beginner

Rust supports loops to repeat code execution: standard for ranges, conditional while loops, and the infinite loop block.

1 Loop Expressions Returning values

In Rust, **`loop`** declares an infinite loop. It can also act as an expression, returning a value via the `break` keyword: `let value = loop { if condition { break 42; } };`.

2 Loops Code

Let's run a program illustrating while loops, range loops, and returning values from loops:

Rust — Loops ▶ Run Code

fn main() {
    // 1. Loop expression returning value
    let mut counter = 0;
    let result = loop {
        counter += 1;
        if counter == 10 {
            break counter * 2; // Returns value from loop
        }
    };
    println!("Result from loop: {}", result);

    // 2. While loop
    let mut num = 3;
    print!("While loop countdown: ");
    while num > 0 {
        print!("{} ", num);
        num -= 1;
    }
    println!();

    // 3. For range loop (1..=3 includes 3)
    print!("For range loop: ");
    for x in 1..=3 {
        print!("{} ", x);
    }
    println!();
}

3 Code Challenge

Challenge: Write a range loop that sums all odd numbers between 1 and 20. Skip the number 11 using the `continue` keyword, and print the computed sum at the end.