fn grade(score: i32) -> &'static str {
    if score >= 80 {
        "A"
    } else if score >= 70 {
        "B"
    } else if score >= 60 {
        "C"
    } else if score >= 50 {
        "D"
    } else {
        "F"
    }
}

fn main() {
    println!("85 -> {}", grade(85)); // A
    println!("72 -> {}", grade(72)); // B
    println!("45 -> {}", grade(45)); // F
}

fn main() {
    let mut count = 1;

    loop {
        println!("{}", count);

        if count == 5 {
            break;
        }

        count += 1;
    }
}

fn main() {
    let mut n = 10;

    while n > 0 {
        println!("{}", n);
        n -= 1;
    }

    println!("Liftoff!");
}

fn main() {
    let numbers = [10, 20, 30, 40, 50];

    for (index, value) in numbers.iter().enumerate() {
        println!("Index {}: {}", index, value);
    }
}

Output:

Index 0: 10
Index 1: 20
Index 2: 30
Index 3: 40
Index 4: 50

fn main() {
    for n in 1..=20 {
        if n % 3 == 0 && n % 5 == 0 {
            println!("FizzBuzz");
        } else if n % 3 == 0 {
            println!("Fizz");
        } else if n % 5 == 0 {
            println!("Buzz");
        } else {
            println!("{}", n);
        }
    }
}