Rust Ownership / Borrow

borrow.rs

fn sum_vectors(a: Vec<i32>, b: Vec<i32>) -> (Vec<i32>, Vec<i32>, Vec<i32>) {
  let mut result: Vec<i32> = vec![0; 3];

  for (i, _item) in a.iter().enumerate() {
    result[i] = a[i] + b[i];
  }

  (a, b, result)
}

fn sum_vectors_borrow(a: &Vec<i32>, b: &Vec<i32>) -> Vec<i32> {
  let mut result: Vec<i32> = vec![0; 3];

  for (i, _item) in a.iter().enumerate() {
    result[i] = a[i] + b[i];
  }

  result
}

fn add_element(a: &mut Vec<i32>, el: i32) {
  a.push(el);
}


fn print_vector(a: &Vec<i32>) {
  for item in a {
    println!("{}", item);
  }
}

fn main() {
  println!("Owned:");
  let (a, b): (Vec<i32>, Vec<i32>) = (vec![1, 2, 3], vec![4, 5, 6]);
  let (a, b, c) = sum_vectors(a, b);
  print_vector(&a);
  print_vector(&b);
  print_vector(&c);

  println!("Borrow:");
  let c = sum_vectors_borrow(&a, &b);
  print_vector(&a);
  print_vector(&b);
  print_vector(&c);

  println!("Mutable ref");
  let mut d = vec![1, 2];
  add_element(&mut d, 3);
  print_vector(&d);
}