Unwrap

In Rust, .unwrap() is a method used on types like Option<T> and Result<T, E> to extract the value inside when you are certain it exists (i.e., it is Some(value) or Ok(value)).

However, if the value is None or Err, .unwrap() will panic (crash your program).

fn main() {
    let some_value: Option<i32> = Some(42);
    let x = some_value.unwrap(); // x = 42
    println!("x: {x}");

    let none_value: Option<i32> = None;
    let y = none_value.unwrap(); // PANIC!
    println!("y: {y}");
}

fn main() {
    let result: Result<i32, &str> = Ok(42);
    let x = result.unwrap(); // x = 42
    println!("x: {x}");

    let err_result: Result<i32, &str> = Err("Something went wrong");
    let y = err_result.unwrap(); // PANIC: "Something went wrong"
    println!("y: {y}");
}

This is how cloudflare “crashed” 20% of the Internet.

Prefer explicit error handling in real-world code to avoid crashes.

• Use .expect("message") to provide a custom panic message.
• Use pattern matching (match or if let) for explicit error handling.
• Use methods like .unwrap_or(default) or ? (the “try” operator) for safer handling.