[Project] Build a small inventory system

In this lesson you combine the structs, enums, vectors, and match expressions covered so far into a simple inventory system. It is the capstone of this Rust introduction.

Real business systems use this combination constantly: represent something like a product with a struct, manage many of them in a vector, and branch on state with an enum and match.

The sample code represents a product (name and quantity) with struct Item, tracks stock level with enum Status, and prints a per-state message with match.

Ownership, borrowing, Option, and Result — everything covered in these lessons — are the foundations you will design around in real systems and tools. Getting into the habit of writing small programs while thinking about ownership is the shortest path to using Rust professionally.

📖 Reference code

enum Status {
    InStock,
    LowStock,
    OutOfStock,
}

struct Item {
    name: String,
    quantity: i32,
}

fn status_of(item: &Item) -> Status {
    if item.quantity == 0 {
        Status::OutOfStock
    } else if item.quantity < 5 {
        Status::LowStock
    } else {
        Status::InStock
    }
}

fn report(items: &Vec<Item>) {
    for item in items {
        let label = match status_of(item) {
            Status::InStock => "In stock",
            Status::LowStock => "Low stock",
            Status::OutOfStock => "Out of stock",
        };
        println!("{}: {} ({})", item.name, item.quantity, label);
    }
}

fn main() {
    let items = vec![
        Item { name: String::from("Notebook"), quantity: 12 },
        Item { name: String::from("Eraser"), quantity: 3 },
        Item { name: String::from("Ruler"), quantity: 0 },
    ];
    report(&items);
}

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run Rust directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).