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🦀 Rust Structs

·298 words·2 mins·
Programming Rust Structs Programming
Table of Contents

Rust Structs
#

Structs let you create custom types that group related data together. They’re similar to tuples, but each piece of data has a name.

Defining Structs
#

Define a struct using the struct keyword:

struct User {
    active: bool,
    username: String,
    email: String,
    sign_in_count: u64,
}

fn main() {
    let user1 = User {
        email: String::from("[email protected]"),
        username: String::from("someusername123"),
        active: true,
        sign_in_count: 1,
    };
    
    println!("User email: {}", user1.email);
}

Mutable Structs
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The entire struct must be mutable to change fields:

fn main() {
    let mut user1 = User {
        email: String::from("[email protected]"),
        username: String::from("someusername123"),
        active: true,
        sign_in_count: 1,
    };
    
    user1.email = String::from("[email protected]");
}

Struct Update Syntax
#

Create instances from other instances:

fn main() {
    let user1 = User {
        email: String::from("[email protected]"),
        username: String::from("someusername123"),
        active: true,
        sign_in_count: 1,
    };
    
    let user2 = User {
        email: String::from("[email protected]"),
        ..user1  // Use remaining fields from user1
    };
}

Tuple Structs
#

Structs without named fields:

struct Color(i32, i32, i32);
struct Point(i32, i32, i32);

fn main() {
    let black = Color(0, 0, 0);
    let origin = Point(0, 0, 0);
    
    println!("First color value: {}", black.0);
}

Unit-Like Structs
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Structs without any fields:

struct AlwaysEqual;

fn main() {
    let subject = AlwaysEqual;
}

Method Syntax
#

Define methods within an impl block:

struct Rectangle {
    width: u32,
    height: u32,
}

impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
    
    fn can_hold(&self, other: &Rectangle) -> bool {
        self.width > other.width && self.height > other.height
    }
}

fn main() {
    let rect1 = Rectangle {
        width: 30,
        height: 50,
    };
    
    println!("Area: {}", rect1.area());
}

Associated Functions
#

Functions that don’t take self as a parameter:

impl Rectangle {
    fn square(size: u32) -> Rectangle {
        Rectangle {
            width: size,
            height: size,
        }
    }
}

fn main() {
    let sq = Rectangle::square(3);
}

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