wiki/content/20200831193417-structs.md

---
date: 2020-08-31
id: 26048172-107d-4ad4-9906-acdf7935dfcb
title: Rust Structs Syntax
---

# Basics

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

fn build_user(email: String, username: String) -> User {
    // When struct field name and parameter name are the same shorthand syntax can be used
    User {
        email,
        username,
        active: true,
        sign_in_count: 1,
    }
}

fn print_data(user: User) {
    println!("User email is: {}", user.email);
    println!("User username is: {}", user.username);
    println!("User sign in count is: {}", user.sign_in_count);
    println!("User active is: {}", user.active);
}

fn main() {
    let user1 = build_user(
        String::from("someone@example.com"),
        String::from("someusername123"),
    );

    println!("User 1");
    print_data(user1);

    let mut user2 = User {
        email: String::from("someone@example.com"),
        username: String::from("someusername123"),
        active: true,
        sign_in_count: 1,
    };
    user2.email = String::from("anotheremail@example.com");

    println!("User 2");
    print_data(user2);
}
```

``` rust

```

# Tuple Struct

``` rust
fn main() {
    struct Color(i32, i32, i32);
    struct Point(i32, i32, i32);

    let black = Color(0, 0, 0);
    let origin = Point(0, 0, 0);
}
```

# Debug trait

To print out debugging information we have the [debug
trait](https://doc.rust-lang.org/std/fmt/trait.Debug.html):

``` rust
#[derive(Debug)]
struct Rectangle {
    width: u32,
    height: u32,
}

fn main() {
    let rect1 = Rectangle {
        width: 30,
        height: 50,
    };

    println!("rect1 is {:?}", rect1);
}
```

# Methods

Methods are like functions, but for structs:

``` rust
#[derive(Debug)]
struct Rectangle {
    width: u32,
    height: u32,
}

impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
}

fn main() {
    let rect1 = Rectangle {
        width: 30,
        height: 50,
    };

    println!(
        "The area of the rectangle is {} square pixels.",
        rect1.area()
    );
}
```

# Associated Functions

These are Rust's take on static functions. They **don't** take `self` as
a parameter

``` rust
#[derive(Debug)]
struct Rectangle {
    width: u32,
    height: u32,
}

impl Rectangle {
    fn area(&self) -> u32 {
        self.width * self.height
    }
    fn square(size: u32) -> Rectangle {
        Rectangle {
            width: size,
            height: size,
        }
    }
}

fn main() {
    let rect1 = Rectangle::square(10);
    println!(
        "The area of the rectangle is {} square pixels.",
        rect1.area()
    );
}
```