Rust — Structs

Basic struct

struct Person {
    name: String,
    age: u32,
}

fn main() {
    let alice = Person {
        name: String::from("Alice"),
        age: 30,
    };

    println!("{} is {}", alice.name, alice.age);
}

Tuple structs

struct Color(u8, u8, u8);
struct Point(f64, f64);

fn main() {
    let red = Color(255, 0, 0);
    let origin = Point(0.0, 0.0);

    println!("Red: ({}, {}, {})", red.0, red.1, red.2);
}

Unit structs

struct Marker;

fn main() {
    let _m = Marker;
}

Methods

struct Rectangle {
    width: f64,
    height: f64,
}

impl Rectangle {
    fn area(&self) -> f64 {
        self.width * self.height
    }

    fn perimeter(&self) -> f64 {
        2.0 * (self.width + self.height)
    }

    fn is_square(&self) -> bool {
        self.width == self.height
    }
}

fn main() {
    let rect = Rectangle { width: 5.0, height: 3.0 };
    println!("Area: {}", rect.area());
    println!("Is square: {}", rect.is_square());
}

Associated functions

struct Circle {
    radius: f64,
}

impl Circle {
    // Associated function (like static method)
    fn new(radius: f64) -> Circle {
        Circle { radius }
    }

    fn area(&self) -> f64 {
        std::f64::consts::PI * self.radius * self.radius
    }
}

fn main() {
    let c = Circle::new(5.0);
    println!("Area: {:.2}", c.area());
}

Multiple impl blocks

struct Counter {
    count: u32,
}

impl Counter {
    fn new() -> Counter {
        Counter { count: 0 }
    }
}

impl Counter {
    fn increment(&mut self) {
        self.count += 1;
    }

    fn get(&self) -> u32 {
        self.count
    }
}

Mini Practice

Write Rust code that:

1. Creates a struct with fields
2. Implements methods with &self and &mut self
3. Creates an associated function
4. Demonstrates tuple structs

Up Next

In the next lesson, you'll learn about Enums — enumerations in Rust.