Question Mark Operator

Use ? to propagate errors concisely.

Difficulty

Intermediate

Code

use std::fs;
use std::io;

fn read_username() -> Result<String, io::Error> {
    let content = fs::read_to_string("username.txt")?;
    Ok(content.trim().to_string())
}

fn main() {
    match read_username() {
        Ok(name) => println!("Hello, {}!", name),
        Err(e) => println!("Error: {}", e),
    }
}

Explanation

This example demonstrates how to use question mark operator in Rust. Read the code carefully to understand the flow. Pay attention to where values are created, borrowed, moved, or consumed.

Key Concepts

• Rust's strong type system catches errors at compile time
• Ownership and borrowing rules ensure memory safety
• Pattern matching makes code expressive and exhaustive

Related Topics

Browse more examples in the error-handling category to build a complete understanding of this topic.