Control Flow

Conditionals

Examples

• Works :

  if number < 10 {
      println!("algo");
  } else if number < 22 {
      println!("outra coisa");
  } else {
      println!("outra coisinha");
  }
  

• Does not work :

  let number = 3;
  
  if number {
      println!("number was three");
  }
  

  • Rust will not automatically try to convert non-Boolean types to a Boolean.

Ternary

let number: i32 = if 2 < 3 { 5 } else { 1 }

• If the if  and else  arms have value types that are incompatible, you'll get an error.

Loops

Loop

loop {
    println!("again!");
    if \condicional {
        break;
    }
}

let mut counter = 0;
let result  = loop {

    counter += 1;

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

• break

  • Exits the loop.

• continue

  • Skip over any remaining code in this iteration of the loop and go to the next iteration.

• Labels

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

    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;
    }
    println!("End count = {count}");
    

While

let mut number = 3;

while number != 0 {
    number -= 1;
}

For

let a = [10, 20, 30, 40, 50];

for element in a.iter() {
    println!("the value is {}", element);
}

// Creates a sequence of numbers from 1 to 3.
for number in (1..4) {
    println!("the value is {}", element);
}
// Same thing
for number in 1..4 {
    println!("the value is {}", element);
}