Rust question mark operator

Rust is awesome language, blazingly fast, low level but of course it can be used in high level targets wery well. Now I will be talk about an interesting operator in Rust: Question Mark Operator.

Everything is about error handling. As you know Rust doesn’t have any try-catch syntax. Instead of there is Result enum. As you remember your first days of start to programming, you didn’t use try-catch, you just return a zero, null, -1 or anything “unvaluable” thing when there is an error. Same thing exist in Rust but this is better way. You can return a Result enum and this has two fields: Ok and Error. As you think if everything is fine, you just return Ok() or Ok(good_variable), but if you something goes wrong you just return Err(any_type_of_error). Let’s look at example code:

fn get_file_contents(file_path: &str) -> Result<String, io::Error> {
  let file = match File::open(file_path) {
    Ok(f) => f,
    Err(e) => return Err(e),
  };
}

This syntax is so common, you can see/make this almost for every Result type. Rust has a solution for this common thing: question mark operator. We can make same thing with a single question mark:

fn get_file_contents(file_path: &str) -> Result<String, io::Error> {
  let file = File::open(file_path)?;
}

As you can see the code become so pretty, understandable and manageable. This is exactly what “question mark operator” does. Happy coding…