Structs, Enums & The Option<T> Type

Why Rust has no NULL: The Option<T> enum (Some vs None) and match expressions

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Rust replaces Null with the Option<T> enum. A value is either Some(value) or None. The compiler forces you to handle the None case explicitly before extracting data.

Eliminating Null Pointer Exceptions with Option<T>

Definition: enum Option<T> { Some(T), None }.

Pattern Matching with match: Exhaustively matches both Some and None states.

The compiler guarantees you cannot accidentally access a None value as if it were valid data.

Pattern Matching with Option<T>

Try It Yourself »

fn find_user_email(user_id: u32) -> Option<String> {
    if user_id == 101 {
        Some(String::from("admin@codexia.org"))
    } else {
        None
    }
}

fn main() {
    let email_result = find_user_email(101);

    // Exhaustive pattern matching enforces handling both states
    match email_result {
        Some(email) => println!("Found user email: {}", email),
        None => println!("User not found!"),
    }
}

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Test Yourself With Exercise

+15 XP

How does Rust represent the potential absence of a value without using null pointers?

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