Shadowing Variables

Immutable Variables Can't Be Changed

Trying to update the value of an immutable variable results in an error. This code sets an initial immutable value with let alfa = 3 and then tries to update it with alfa = 5 which causes an error.

Click Run to see an example of what that looks like.

#[allow(unused_variables)]
#[allow(unused_assignments)]
fn main() {
  let alfa = 3;
  alfa = 5;
}

Shadowing Variables Works

While you can't update an immutable variable, you can define a new one with the same name. This is called shadowing.

Enter and run this code for an example

fn main() {
  let alfa = 3;
  println!("The value is {alfa}");

  let alfa = 5;
  println!("The value is {alfa}");
}

CODE EDITOR

TODO

• Come up with examples of when you might want to shadow a variable (changing type might be one, but I don't know yet why you would do that instead of making a new variable)