Handling errors with match in Rust - Mini Project: Build & Apply

Handling errors with match

📖 Scenario: You are writing a small Rust program that reads a number from a string and handles possible errors gracefully.

🎯 Goal: Build a Rust program that converts a string to a number using parse() and uses match to handle success and error cases.

📋 What You'll Learn

Create a string variable with a number value

Create a variable to hold the parsed result using parse()

Use match to handle Ok and Err cases

Print the parsed number if successful or an error message if parsing fails

💡 Why This Matters

🌍 Real World

Parsing user input or data from files often requires handling errors to avoid program crashes.

💼 Career

Understanding error handling with <code>match</code> is essential for writing safe and reliable Rust programs.

1

Create a string with a number

Create a variable called number_str and set it to the string "42".

Rust

# Your code here

Hint

Use let to create the variable and put the number inside quotes.

2

Parse the string to a number

Create a variable called parsed_number and set it to the result of calling number_str.parse::().

Rust

let number_str = "42";
# Your code here

Hint

Use parse::() to convert the string to a 32-bit integer.

3

Use match to handle parsing result

Use match parsed_number with arms for Ok(num) and Err(e). Inside Ok(num), create a variable number equal to num. Inside Err(e), create a variable error_message equal to e.to_string().

Rust

let number_str = "42";
let parsed_number = number_str.parse::();
# Your code here

Hint

Use match to check if parsing was successful or not.

4

Print the result or error message

Inside the Ok(num) arm, add println!("Parsed number: {}", num);. Inside the Err(e) arm, add println!("Failed to parse number: {}", e);.

Rust

let number_str = "42";
let parsed_number = number_str.parse::();

match parsed_number {
    Ok(num) => {
        let number = num;
        // Your code here
    },
    Err(e) => {
        let error_message = e.to_string();
        // Your code here
    }
}

Hint

Use println! to show the number or error message.