Day 1

⚠️ Important Note

We use clone() in this example, but we are not claiming it is the optimal approach. The goal here is to present a solution that helps illustrate Rust's ownership system in a simple way. As the story unfolds in the next challenge, we'll dive into more efficient patterns. This example is intentionally simplified for the sake of education and storytelling.

Enjoy!

The Story

It's 1st December and the countdown has just begun. The elves are busy preparing for the Christmas and Santa is busy checking the list of children who have been good this year. It was supposed to be a smooth day until all of a sudden two of santa's elves burst into Santa's office with a problem.

“Santa!” one of the elves shouted. “The code won’t compile! We’ve hit a wall, and it’s all Rust’s fault!”

Santa, sipping his triple-shot peppermint latte, raised an eyebrow. “Rust’s fault? Or your fault?”

“It’s the ownership rules!” the other elve blurted. “I think we violated them, we’re used to Python, where variables just... work. Look at this!”

The elves tried their best, here is what they've written so far:

fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message);
 
    println!("{}", gift_message);
}
 
fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

However, the code won't compile. Can you help the elves attach the message to the present and print the message too?

Maybe... if there was only a way to get a clone of the message and pass it to the function. 🤔

Hints

You must not change the attach_message_to_present function.
Use clone() to create a clone of the gift_message and pass it to the function.

Editor not available on Mobile!

In order to solve the challenge, please visit this page on a desktop computer.

Solutions

Elena Sukmanova

sukman

39 minutes ago

399.17ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

M Bussonnier

Carreau

an hour ago

383.39ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

rm-rf

admiraladmirable

2 hours ago

360.02ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Manta

Soecka

2 hours ago

374.09ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Tobias Vicenti

SchnobiTobi

2 hours ago

382.92ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Oliver Horn

ohorn

2 hours ago

362.06ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Markus Wege

markuswege

3 hours ago

421.08ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Michel Casabianca

c4s4

3 hours ago

360.36ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Ruspoetin

3 hours ago

369.92ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

recursivemaze

3 hours ago

471.48ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

brunoalef7

3 hours ago

373.10ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Len Remmerswaal

LenRemmerswaal

4 hours ago

349.94ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

gkapkowski-saucelabs

4 hours ago

379.63ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Patrick G

doeixd

6 hours ago

419.96ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Dasun Pubudumal

dasunpubudumal

6 hours ago

373.24ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Nikita

robotomize

7 hours ago

363.51ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

0x776a

midnightexigent

8 hours ago

378.24ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

rawar089

8 hours ago

425.96ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

zealsham

8 hours ago

349.46ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Sergei Barbarash

sgt

9 hours ago

352.07ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

fletawe-haulogy

10 hours ago

430.05ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Hudson C. Dalprá

dalprahcd

10 hours ago

355.62ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

mrsalo

11 hours ago

419.47ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

WuHan0608

11 hours ago

379.70ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

neonwarp

11 hours ago

392.01ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Shun

aockgonnabefree

12 hours ago

388.92ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

LaserPH (Ethan)

LaserPH

14 hours ago

438.62ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

theandi667

15 hours ago

362.98ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

var4yn

15 hours ago

573.69ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Jeff Glaum

jeffglaum

16 hours ago

788.02ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Jeff Glaum

jeffglaum

16 hours ago

427.94ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

rubonz

16 hours ago

397.47ms

175.37kb

use std::ops::Deref;
const SNOWBALL_WEIGHT_KG: f64 = 0.2;
const SNOWBALL_WEIGHT_LB: f64 = 0.441;
pub struct SnowKg(pub f64);
impl SnowKg {
    pub fn new(kg: f64) -> Self {
        SnowKg(kg)
    }
}
impl Deref for SnowKg {
    type Target = f64;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
pub struct SnowLb(pub f64);
impl SnowLb {
    pub fn new(lb: f64) -> Self {
        SnowLb(lb)
    }
}
impl Deref for SnowLb {
    type Target = f64;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
pub struct Snowball(pub i64);
impl Snowball {
    pub fn new(snowballs: i64) -> Self {
        Snowball(snowballs)
    }
}
impl Deref for Snowball {
    type Target = i64;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl From<SnowKg> for Snowball {
    fn from(kg: SnowKg) -> Self {
        let snowballs = (*kg / SNOWBALL_WEIGHT_KG).round() as i64;
        Snowball(snowballs)
    }
}
impl From<SnowLb> for Snowball {
    fn from(lb: SnowLb) -> Self {
        let snowballs = (*lb / SNOWBALL_WEIGHT_LB).round() as i64;
        Snowball(snowballs)
    }
}
pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone());
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

albert chang

0xkuznechik

17 hours ago

356.74ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Kj

kj-9

19 hours ago

398.01ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

jon-a-miller

20 hours ago

334.31ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

nikwi

20 hours ago

400.25ms

98.44kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone());
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

nikwi

20 hours ago

400.71ms

98.44kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone());
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Ryan Plauche

plauche

21 hours ago

348.96ms

98.44kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone());
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

David Pathakjee

dpathakj

a day ago

443.72ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Kada

Kada-quantum

a day ago

342.69ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Shaphil

a day ago

344.15ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Vabka

vabka

a day ago

341.23ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

jeremyp

jpekmez

a day ago

355.35ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

IvanyaK

a day ago

422.60ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Maxime Biette

mbiette

a day ago

347.16ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Edgar Christian

edgarcnp

a day ago

406.37ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Yuankun Zhang

yuankunzhang

a day ago

359.65ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Matt Tuusberg

tuusberg

a day ago

554.60ms

98.44kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); //
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Li Feng

maplestarplayl

a day ago

531.01ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}

Rostyslav Bohomaz

rostyq

a day ago

386.24ms

98.47kb

pub fn main() {
    let gift_message = String::from("Merry Christmas! Enjoy your gift!");
    attach_message_to_present(gift_message.clone()); // <-- Add a `.clone()` here!
    println!("{}", gift_message);
}
// Don't change this function!
pub fn attach_message_to_present(message: String) {
    println!("The present now has this message: {}", message);
}