Rust Fundamentals Exercises

This repository contains a collection of exercises designed to learn and practice the fundamental concepts of the Rust programming language.

The project is structured as a library (lib.rs) with multiple modules, separating definitions from the main execution loop and integration tests.

📝 Features & Exercises

1. String Transposition

A function that takes a reference to a vector of strings and transposes them. The output vector strings are formed by grouping the n-th characters of each input string. The output strings' length is bounded by the shortest string in the input vector.

2 & 4. Rational Numbers & Operator Overloading

A module implementing rational numbers (Rational).

• Core Logic: Fractions are automatically reduced to their lowest terms upon creation using the Greatest Common Divisor (GCD).
• Methods: Sum, product, inverse, and comparison.
• Trait Implementation: Standard library traits are heavily used here to make the struct behave like primitive numbers. Includes custom implementations for std::ops::Add, std::ops::Mul, std::fmt::Display, and std::cmp::PartialOrd, alongside derived traits like Debug and PartialEq.

3. Grid Survival Game

A 2D terminal-based game simulation.

• The Grid: An n x n matrix surrounded by walls. Inner cells can be empty, contain food (increases strength), or poison (decreases strength).
• The Player: Starts with a given strength and a random direction (Up, Down, Left, Right).
• Mechanics: Each turn, a coin is flipped. Heads means the player keeps moving in the current direction; Tails means the player picks a new random direction. Hitting a wall makes the player bounce in the opposite direction.
• Win/Loss: The game ends in victory if the player survives for a maximum number of moves, or in defeat if their strength drops to 0 or below.

5. Vending Machine (State Design Pattern)

An object-oriented approach to a Vending Machine using Rust's Trait Objects to implement the State Pattern.

• Context: The DistributoreAutomatico holds an inventory (HashMap<String, i32>), the currently selected product, and its current State.
• States: Transitions between InAttesaCarta, CartaAccettata, SelezionatoProdotto, ProdottoEsaurito, and ProdottoDisponibile.
• Actions: Depending on the current state, actions like inserting a card, selecting a product, confirming, or canceling will have different behaviors and outputs.

6. Family Tree (Shared Ownership & Interior Mutability)

A genealogy model that explores Rust's smart pointers for building graph-like, mutable, cyclic data structures.

• The Nodes: Each Person holds a name plus optional references to a mother, father, and a vector of children. Shared ownership across the tree is handled with Rc<RefCell<Person>> — Rc allows multiple owners (a person is referenced both as a parent's child and as its own node), while RefCell enables interior mutability so relationships can be wired up after creation.
• The Collection: People wraps a vector of persons and exposes the registry API: add_person (rejects duplicate names via Result), search_person, set_mother, set_father, and print (falls back to "unknown" when a parent is missing).
• Traversal: descendants walks the tree recursively, using a seen-list guard to ensure no name is ever produced twice.

7. English Auction (Concurrency: Threads, Channels & Shared State)

A concurrent implementation of the English Auction protocol where each actor is its own thread.

• Actors: One auctioneer thread plus n participant threads, each spawned independently.
• Message Passing: Communication runs entirely over mpsc channels — participants send PartecipantMessage (Ready, Bid, Exit) to the auctioneer, while the auctioneer broadcasts AuctioneerMessage (Start, NewPrice, Winner) back to every active participant.
• Protocol Flow: After all participants signal Ready, the auctioneer announces the product and starting price. Each round, participants either bid above the current price or drop out; every valid raise is broadcast to the remaining bidders. The auction ends once all participants have exited.
• Outcome: The item is sold only if the final price clears the reserve_price. The result (product, final price, winning participant) is written exactly once at the end into an Arc<Mutex<AuctionOutcome>>, the single piece of shared state read by participants — keeping with the rule that channels drive the protocol and shared memory is used only for the final result.

🚀 How to Run

The main executable (main.rs) currently runs the English Auction simulation (Exercise 7). The Game module (Exercise 3) and earlier main setups are kept as commented-out blocks you can swap back in.

cargo run

🧪 Testing

All modules are strictly tested using Rust's built-in testing framework. Tests are separated into their own directory (tests/).

To run the entire test suite:

cargo test