[易学易懂系列|rustlang语言|零基础|快速入门|（11）]

Posted 2020-11-26 gyc567

[易学易懂系列|rustlang语言|零基础|快速入门|（11）]

有意思的基础知识

Structs

我们今天来看看数据结构：structs.

简单来说，structs，就是用来封装相关数据的一种数据类型。

一般来说， struct 的命名方式为驼峰方式如： CamelCase

在Rust有以下几种定义struct的方式：

1. C-like structs （C语言形式的struct）
2. Tuple structs (元组形式的struct)
3. Unit structs （单元struct）

在Rust，面向对象抽象，一般由struct和trait(特征)来实现，即structs来

封装属性数据，而trait用来封装方式，再由impl来关联。

我们来看看代码：

C语言形式的struct

// Struct Declaration
struct Color {
    red: u8,
    green: u8,
    blue: u8
}

fn main() {
  // Creating an instance
  let black = Color {red: 0, green: 0, blue: 0};

  // Accessing its fields using dot notation
  println!("Black = rgb({}, {}, {})", black.red, black.green, black.blue); //Black = rgb(0, 0, 0)

  // Structs are immutable by default, use `mut` to make it mutable but doesn't support field level mutability
  let mut link_color = Color {red: 0,green: 0,blue: 255};
  link_color.blue = 238;
  println!("Link Color = rgb({}, {}, {})", link_color.red, link_color.green, link_color.blue); //Link Color = rgb(0, 0, 238)

  // Copy elements from another instance
  let blue = Color {blue: 255, .. link_color};
  println!("Blue = rgb({}, {}, {})", blue.red, blue.green, blue.blue); //Blue = rgb(0, 0, 255)

  // Destructure the instance using a `let` binding, this will not destruct blue instance
  let Color {red: r, green: g, blue: b} = blue;
  println!("Blue = rgb({}, {}, {})", r, g, b); //Blue = rgb(0, 0, 255)

  // Creating an instance via functions & accessing its fields
  let midnightblue = get_midnightblue_color();
  println!("Midnight Blue = rgb({}, {}, {})", midnightblue.red, midnightblue.green, midnightblue.blue); //Midnight Blue = rgb(25, 25, 112)

  // Destructure the instance using a `let` binding
  let Color {red: r, green: g, blue: b} = get_midnightblue_color();
  println!("Midnight Blue = rgb({}, {}, {})", r, g, b); //Midnight Blue = rgb(25, 25, 112)
}

fn get_midnightblue_color() -> Color {
    Color {red: 25, green: 25, blue: 112}
}

元组形式的struct

struct Color(u8, u8, u8);
struct Kilometers(i32);

fn main() {
  // Creating an instance
  let black = Color(0, 0, 0);

  // Destructure the instance using a `let` binding, this will not destruct black instance
  let Color(r, g, b) = black;
  println!("Black = rgb({}, {}, {})", r, g, b); //black = rgb(0, 0, 0);

  // Newtype pattern
  let distance = Kilometers(20);
  // Destructure the instance using a `let` binding
  let Kilometers(distance_in_km) = distance;
  println!("The distance: {} km", distance_in_km); //The distance: 20 km
}

单元struct

struct Electron;

fn main() {
  let x = Electron;
}

以上，希望对你有用。

如果遇到什么问题，欢迎加入：rust新手群，在这里我可以提供一些简单的帮助，加微信：360369487，注明：博客园+rust

https://learning-rust.github.io/docs/b2.structs.html