Rust Functions

fn main(){
  let mut arr:[i32; 5] = [2,4,6,8,10];
  multiply(arr);
  println!("The array is : {:?}", multiply(arr));
}
fn multiply (mut arr: [i32 ; 5]) -> [i32 ; 5]{
  arr[2] = 90;
  for mut i in 0..5 {
      arr[i] = arr[i] * arr[2];
  }
  return arr;
}

fn main(){
  let mut array: [i32 ; 5] = [1,2,3,4,6];
  print\_arrays(array);
  println!("The elements: {array:?}");
}
fn print\_arrays(mut array:[i32; 5]) {
  array[0] = 89;
  array[1] = 90;
  array[2] = 91;
  array[3] = 92;
  array[4] = 93;
  println!("The elements: {array:?}");
}

fn main(){
  let (mut radius, mut pi) = (3.0, 3.14);
  let(area, _perimeter) = calculate (
      &mut radius,
      &mut pi
  );
  println!("The area and the perimeter of the circle are: {area} & {\_perimeter}");
}
fn calculate(radius : &mut f64, pi: &mut f64) -> (f64, f64){
  let perimeter = 2.0 * *pi * *radius;
  let area = *pi * *radius * *radius;
  return (area, perimeter);
}

fn main(){
  let mut by\_ref = 3;      // => 3
  power\_of\_three(&mut by_ref);
  println!("{by\_ref}");  // => 9
}
fn power\_of\_three(by_ref: &mut i32){
  // de-referencing is important
  *by_ref = *by_ref * *by_ref;
  println!("{by\_ref}");  // => 9
}

fn main()
{
  let x:u32 = 10;
  let y:u32 = 20;

  // => 200
  println!("Calc: {}", cal\_rect(x, y));
}
fn cal\_rect(x:u32, y:u32) -> u32
{
  x * y
}

fn print\_message(){
  println!("Hello, QuickRef.ME!");
}
fn main(){
  //Invoking a function in Rust.
  print\_message();
}