Structs Challenge

To practice what you've learned, let's implement a simple struct for a book in a library. We'll create a Book struct with a few fields and methods to manage the book's information.

Here is our Book struct:

struct Book {
    title: String,
    author: String,
    available: bool,
}

You are required to implement a few functionalities in the Book struct:

• Add an associated function called new() that creates a new book instance with a default value of available set to true.
• Add a borrow() method to set the available field to false.
• Add a return_book() method to set the available field to true.
• Add a method is_available() that returns a boolean indicating if the book is available or not.
• Create a few book instances and demonstrate borrow and returning books.

Give it a go by yourself and try not to look at the solution until you've given it a good try. After you finish it or get stuck, you can check the solution below.

Great job at giving it a try. Let's solve the problem together and see if you got it right.

First things first, let's define the Book struct:

struct Book {
    title: String,
    author: String,
    available: bool,
}

We need to add a new() associated function to create a new book instance with a given title and author, and set available to true.

impl Book {
    fn new(title: &str, author: &str) -> Self {
        Self {
            title: title.to_string(),
            author: author.to_string(),
            available: true,
        }
    }
}

We need to add a borrow() method to set the available field to false.

impl Book {
    fn borrow(&mut self) {
        self.available = false;
    }
}

We need to add a return_book() method to set the available field to true.

impl Book {
    fn return_book(&mut self) {
        self.available = true;
    }
}

We need to add a method is_available() that returns a boolean indicating if the book is available or not.

impl Book {
    fn is_available(&self) -> bool {
        self.available
    }
}

Let's create a few book instances and demonstrate the borrow and returning books methods.

fn main() {
    let mut book1 = Book::new("1984", "George Orwell");
    let mut book2 = Book::new("To Kill a Mockingbird", "Harper Lee");
 
    println!("Is '{}' available? {}", book1.title, book1.is_available());
    book1.borrow();
    println!("Is '{}' available? {}", book1.title, book1.is_available());
 
    book1.return_book();
    println!("Is '{}' available? {}", book1.title, book1.is_available());
 
    println!("Is '{}' available? {}", book2.title, book2.is_available());
    book2.borrow();
    println!("Is '{}' available? {}", book2.title, book2.is_available());
}

Running the code:

> Is '1984' available? true
> Is '1984' available? false
> Is '1984' available? true
> Is 'To Kill a Mockingbird' available? true
> Is 'To Kill a Mockingbird' available? false

This simple challenge helps you practice basic struct functionalities, including creating instances, mutating fields, and checking conditions.

In the next lesson, we're going to explore how structs work with ownership and borrowing in Rust.