Using 'match' with 'Option'

Part of the Logic & Flow section of Coddy's Rust journey — lesson 36 of 66.

Now that you understand what Option is, let's learn the most common and explicit way to handle it: using a match expression. This approach forces you to consider both possible cases - when there's a value and when there isn't.

The match expression works perfectly with Option because you can create arms for both variants:

let maybe_name = Some("Alice".to_string());

match maybe_name {
    Some(name) => println!("Hello, {}!", name),
    None => println!("Hello, stranger!"),
}

Notice how the Some(name) arm extracts the value from inside the Some variant. The variable name now contains the actual String, not the Option. This is called destructuring - you're pulling the inner value out of the wrapper.

The None arm handles the case where there's no value, allowing you to provide alternative behavior like showing a default message or taking a different action entirely.

Challenge

Easy

You will receive a student name as input. The name might be present in the system or it might be missing. Create an Option<String> that contains Some(name) if the name is not empty, or None if the name is empty. Use a match expression to handle both cases and print the appropriate message.

Requirements:

Read the input as a string (student name)
Trim any whitespace from the input using .trim()
Create an Option<String> variable:
- If the trimmed name is not empty, assign Some(name.to_string())
- If the trimmed name is empty, assign None
Use a match expression to handle both variants of the Option
In the Some(name) arm, print: Welcome, [name]!
In the None arm, print: No name provided

Input:

A single line containing either a student name or an empty line

Output:

If a name is provided: Welcome, [name]!
If no name is provided (empty input): No name provided

Cheat sheet

Use a match expression to handle Option values by creating arms for both variants:

let maybe_name = Some("Alice".to_string());

match maybe_name {
    Some(name) => println!("Hello, {}!", name),
    None => println!("Hello, stranger!"),
}

The Some(name) arm uses destructuring to extract the inner value from the Some variant. The variable name contains the actual value, not the Option wrapper.

The None arm handles the case where there's no value, allowing you to provide alternative behavior.

Try it yourself

use std::io;

fn main() {
    // Read input
    let mut input = String::new();
    io::stdin().read_line(&mut input).expect("Failed to read line");
    let name = input.trim();
    
    // TODO: Create an Option<String> based on whether the name is empty or not
    
    // TODO: Use a match expression to handle Some and None cases and print the appropriate message
}