Chapter 01: Quest App: Showing Your Progress (Output)

published:

tags: [ #rust, #programming, #tutorial, #cli, #quest app, #education, #kids, #children, #young, #learners ]

Hey there, Young Coder!

You've started your very own Rust project and explored its first bits of code. Now, let's learn how to make your Rust program talk back to you! This is super important for our Quest App so it can show you your quests.

Making Your Program Talk: println!

In Rust, the easiest way to make your program display text on the screen (your terminal) is by using a special command called println!. It's like your program saying something out loud!

Here's how it works:

fn main() {
  // This will print "Hello, Quest Master!"
  println!("Hello, Quest Master!");

  // This will print another message
  println!("Are you ready for an adventure?");
}

When you run this code, you'll see both sentences appear on separate lines in your terminal. The ! at the end of println means it's a "macro", which is a bit like a super-powered function in Rust.

Storing Your Quests: The Vec (Vector)

For our Quest App, we need a way to store multiple quests. Imagine a list where you write down all your tasks. In Rust, we have something similar called a Vec (pronounced "veck", short for Vector). It's a growable list where you can keep many things, like our quest descriptions!

Let's make a Vec to hold a couple of sample quests:

fn main() {
    // Create an empty list (Vec) where we'll store our quests.
    // We tell Rust it will hold words (Strings).
    let mut quests: Vec<String> = Vec::new();

    // Add our first quest to the list
    quests.push(String::from("Explore the mysterious forest"));

    // Add another quest to the list
    quests.push(String::from("Learn a new Rust command"));

    // Now, let's make our program tell us what quests we have!
    println!("--- Your Current Quests ---");

    // This special loop will go through each quest in our 'quests' list
    for quest in quests {
        println!("- {}", quest); // And print each one!
    }

    println!("---------------------------");
}

What's Happening Here?

  1. let mut quests: Vec<String> = Vec::new();

    • let mut means we're creating a new variable named quests that can be changed (mut for mutable).
    • Vec<String> tells Rust that quests will be a list (Vec) containing text (String).
    • Vec::new() creates an empty list for us to start with.

  2. quests.push(String::from("..."));

    • The .push() command is how we add new items to our quests list.
    • String::from("...") turns our simple text into a String that can be stored in our Vec.

  3. for quest in quests { ... }

    • This is a for loop! It's a way to do something for each item in a list.
    • For every quest (which is what we call each item temporarily) in our quests list, it will run the code inside the {}.

  4. println!("- {}", quest);

    • Inside the loop, println! is used again.
    • The {} is a special placeholder. Rust will replace {} with the value of the quest variable for each item in the list. So, it will print "- Explore the mysterious forest", then "- Learn a new Rust command".

Your Turn

Try changing your src/main.rs file to match the code above.

Then, run your program from the terminal:

cargo run

You should see your program list out your two quests! This is a super important step for building our Quest App, as it lets you see all the quests you have to do! Great job!