Week 1 Review & Practice

Week 1 Wrap-up

Congratulations on finishing your first week with Rust! You’ve navigated the most challenging part of the learning curve: understanding how Rust thinks about memory and safety.

What We’ve Covered

• Day 1: Installation and Cargo.
• Day 2: Immutability vs. Mutability and Shadowing.
• Day 3: Scalars (i32, char) and Compounds (Tuples, Arrays).
• Day 4: Functions, Statements vs. Expressions.
• Day 5: If/Else as expressions and Loop types.
• Day 6: The 3 Rules of Ownership.

Practice Project: Geometry CLI

Today, you’ll build a CLI tool that calculates the area of different shapes. This will practice variables, functions, control flow, and user input.

Step 1: Create the Project

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cargo new shape_calc
cd shape_calc

Step 2: Getting User Input

To read from the terminal, we’ll use the standard library io.

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use std::io;

fn main() {
    println!("Welcome to Shape Calc!");
    
    loop {
        println!("\nSelect a shape: (1) Rectangle (2) Circle (3) Exit");
        
        let mut choice = String::new();
        io::stdin()
            .read_line(&mut choice)
            .expect("Failed to read line");

        let choice: u32 = match choice.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        };

        if choice == 1 {
            calculate_rectangle();
        } else if choice == 2 {
            calculate_circle();
        } else if choice == 3 {
            break;
        }
    }
}

fn calculate_rectangle() {
    // Your code here: Get width/height and print area
}

fn calculate_circle() {
    // Your code here: Get radius and print area (Area = 3.14 * r * r)
}

Project Requirements

1. Implement calculate_rectangle and calculate_circle.
2. Use functions that return values for the actual math.
3. Handle invalid input (like letters instead of numbers) using match (don’t worry about the details of match yet, just use the pattern in the example).

Self-Check Quiz

1. Can I explain why let x = 5; x = 6; fails?
2. Do I know when to use a Tuple vs. an Array?
3. Can I identify an Expression vs. a Statement?
4. Do I understand why let s2 = s1 might make s1 unusable?

Summary

You’ve built a solid foundation. While Ownership might still feel a bit “mystical,” it will become second nature as we dive into Borrowing and References next week.

Next Steps

In Week 2, we solve the “Ownership problem” with Borrowing and References, learn about Slices, and start organizing data with Structs!