Formatting output in Rust - Mini Project: Build & Apply

Formatting output

📖 Scenario: You are creating a simple Rust program to display product prices clearly for a small shop.

🎯 Goal: Learn how to format output in Rust using println! with placeholders and formatting options.

📋 What You'll Learn

Create a dictionary (HashMap) with product names and prices

Create a variable for a price threshold

Use a loop to print products with prices formatted to 2 decimal places

Print the formatted output lines

💡 Why This Matters

🌍 Real World

Formatting prices clearly is important in shops, invoices, and reports to make numbers easy to read and professional.

💼 Career

Many programming jobs require formatting output for user interfaces, reports, or logs, making this skill very useful.

1

Create the product prices HashMap

Create a HashMap called products with these exact entries: "Apple" with price 0.99, "Banana" with price 0.59, and "Cherry" with price 2.99.

Rust

use std::collections::HashMap;

// Create the products HashMap with prices
// Your code here

Need a hint?

Use HashMap::new() and insert to add each product and price.

2

Add a price threshold variable

Inside the main function, create a variable called threshold and set it to 1.00.

Rust

use std::collections::HashMap;

fn main() {
    let mut products = HashMap::new();
    products.insert("Apple", 0.99);
    products.insert("Banana", 0.59);
    products.insert("Cherry", 2.99);

    // Create the threshold variable
    // Your code here
}

Need a hint?

Use let threshold = 1.00; inside main.

3

Loop and format output

Use a for loop with variables product and price to iterate over products.iter(). Inside the loop, use println! to print each product and price formatted to 2 decimal places using {:.2}.

Rust

use std::collections::HashMap;

fn main() {
    let mut products = HashMap::new();
    products.insert("Apple", 0.99);
    products.insert("Banana", 0.59);
    products.insert("Cherry", 2.99);

    let threshold = 1.00;

    // Loop over products and print formatted prices
    // Your code here
}

Need a hint?

Use for (product, price) in products.iter() and println!("{}: ${:.2}", product, price);.

4

Print products above threshold

Modify the for loop to print only products with a price greater than threshold. Use println! to print the product name and price formatted to 2 decimal places.

Rust

use std::collections::HashMap;

fn main() {
    let mut products = HashMap::new();
    products.insert("Apple", 0.99);
    products.insert("Banana", 0.59);
    products.insert("Cherry", 2.99);

    let threshold = 1.00;

    // Print only products with price > threshold
    // Your code here
}

Need a hint?

Use an if statement inside the loop to check if *price > threshold.