Result enum in Rust - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Result enum in Rust?

The Result enum is a type used for error handling. It has two variants: Ok for success and Err for failure.

beginner

What are the two variants of the Result enum?

Ok(T) which holds a success value of type T, and Err(E) which holds an error value of type E.

beginner

How do you handle a Result value in Rust?

You can use match to check if it is Ok or Err, then handle each case accordingly.

intermediate

What does the unwrap() method do on a Result?

It returns the success value if Ok, but causes the program to panic if it is Err.

intermediate

Why is using Result better than using panic! directly?

Because Result forces you to handle errors explicitly, making your program more reliable and preventing unexpected crashes.

What does Result<T, E> represent in Rust?

A A function that always returns an error

B A way to panic the program

C A type for storing multiple values

D A value that can be either success (<code>Ok</code>) or error (<code>Err</code>)

Result<T, E> is used to represent either success (Ok) or failure (Err) in Rust.

Which method on Result will cause a panic if the value is Err?

A is_ok()

B expect()

C unwrap()

D map()

unwrap() returns the success value or panics if it is an error.

How do you safely handle both Ok and Err variants of a Result?

A Using <code>unwrap()</code> always

B Using <code>match</code> to check each variant

C Ignoring the <code>Err</code> variant

D Using <code>panic!</code> directly

Using match lets you handle success and error cases explicitly.

What is the type of the value inside Ok in Result<T, E>?

A T

B E

C Result

D Option

The Ok variant holds a value of type T.

Why should you prefer Result over panicking in Rust?

A Because <code>Result</code> forces explicit error handling

B Because panics are faster

C Because <code>Result</code> hides errors

D Because panics never stop the program

Result encourages you to handle errors clearly, avoiding unexpected crashes.

Explain what the Result enum is and how it helps in error handling in Rust.

Think about how Rust uses Result to avoid crashes.

Describe how you would use match to handle a Result value in a Rust program.

Imagine you get a Result from a function and want to do different things for success or error.