Destructuring

Destructuring is unpacking a value into separate named pieces all at once, like opening a gift box and taking out each item.

In this page:

Destructuring a Tuple
Destructuring a Struct
Ignoring Fields with ..
Discarding Values with _

Destructuring a Tuple

A let statement can destructure a tuple directly into multiple named variables in one line, instead of accessing each element with .0, .1, and so on.

Example: Destructuring a Tuple

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fn main() {
    let point = (3, 7);
    let (x, y) = point;
    println!("x={}, y={}", x, y);
}

Destructuring a Struct

Struct fields can be destructured into local variables of the same names directly in a let statement, using the struct's field names as the pattern.

Example: Destructuring a Struct

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struct Point {
    x: i32,
    y: i32,
}

fn main() {
    let p = Point { x: 5, y: 9 };
    let Point { x, y } = p;
    println!("x={}, y={}", x, y);
}

Ignoring Fields with ..

When you only need a few fields from a larger struct, .. in the pattern tells Rust to ignore all remaining fields without naming them individually.

Example: Ignoring Fields with ..

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struct Config {
    width: u32,
    height: u32,
    fullscreen: bool,
}

fn main() {
    let cfg = Config { width: 1920, height: 1080, fullscreen: true };
    let Config { width, .. } = cfg;
    println!("Width: {}", width);
}

Discarding Values with _

The underscore pattern _ matches any value while discarding it, useful in destructuring or function parameters when a value must be present but is not actually needed.

Example: Discarding Values with _

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fn main() {
    let (first, _, third) = (1, 2, 3);
    println!("first={}, third={}", first, third);
}

Common Mistakes

Trying to destructure only some fields of a struct without using .. to explicitly ignore the rest, which is a compile error.
Forgetting the _ pattern can be used to intentionally discard a value you don't need during destructuring.
Assuming destructuring a reference automatically dereferences everything -- sometimes an explicit & pattern or .clone() is needed.

Chapter Summary

Destructuring extracts multiple named values from a tuple, struct, or enum in a single let or match.
The .. pattern can be used to ignore remaining fields you don't care about.
The _ pattern matches and discards any single value without binding it to a name.
Destructuring works in let statements, function parameters, and match arms alike.

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Destructuring

Destructuring a Tuple

Destructuring a Struct

Ignoring Fields with ..

Discarding Values with _

Chapter Quiz — Complete all 7 topics to unlock

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