Rust3 Using Structs to Structure Related Data Enums and Pattern Matching

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Rust学习笔记

Rust编程语言入门教程课程笔记

参考教材: The Rust Programming Language (by Steve Klabnik and Carol Nichols, with contributions from the Rust Community)

Lecture 5: Using Structs to Structure Related Data

// define a struct
#[derive(Debug)]
struct User{username: String,email: String,sign_in_count: u64,active: bool, // trailing comma is allowed
}// rectangle struct
#[derive(Debug)]
struct Rectangle{width: u32,height: u32,
}impl Rectangle{// method to calculate the area of a rectanglefn area(&self) -> u32{self.width * self.height}// method to check if a rectangle can hold another rectanglefn can_hold(&self, other: &Rectangle) -> bool{self.width > other.width && self.height > other.height}// associated functionfn square(size: u32) -> Rectangle{ // does not take self as parameterRectangle{width: size,height: size,}}
}fn main() {// create an instance of structlet mut user = User{email: String::from("abc@gmail.com"),username: String::from("abc"),active: true,sign_in_count: 1,};println!("{},{},{},{}", user.email, user.username, user.active, user.sign_in_count);// change the value of the structuser.email = String::from("abc_plus@gmail.com");println!("{}", user.email);// create a new instance of struct using functionlet user2 = build_user(String::from("user2@gmail.com"), String::from("user2"));// create a new instance of struct using struct update syntaxlet _user3 = User{email: String::from("user3@gmail.com"),username: String::from("user3"),..user2 // use the remaining fields from user2};// create a tuple structstruct Color(i32, i32, i32);let _black = Color(0, 0, 0);// create a unit struct//struct UnitStruct;// no fields//calculate the area of a rectanglelet rect = Rectangle{width: 30,height: 50,};// create a method for the structprintln!("The area of the rectangle is {} square pixels.", rect.area());println!("{:#?}", rect);let rect2 = Rectangle{width: 10,height: 40,};println!("Can rect hold rect2? {}", rect.can_hold(&rect2));// create a square using associated functionlet square = Rectangle::square(3);println!("The area of the square is {} square pixels.", square.area());
}// create a function that returns a struct
fn build_user(email: String, username: String) -> User{User{email: email,username: username,active: true,sign_in_count: 1,}
}

Lecture 6: Enums and Pattern Matching

//create an enum
#[derive(Debug)]
enum IpAddrKind{V4,V6,
}//create an enum with data
// enum IpAddrKindWithData{
//     V4(u8, u8, u8, u8),
//     V6(String),
// }//four = IpAddrKind::V4(127, 0, 0, 1);#[derive(Debug)]
struct IpAddr {kind: IpAddrKind,address: String,
}#[derive(Debug)]
enum Message{Quit,Move {x: i32, y: i32},Write(String),ChangeColor(i32, i32, i32),
}impl Message{fn call(&self){//method body would be defined hereprintln!("Message: {:?}", self);}
}
#[derive(Debug)]
enum Coin{Penny,Nickel,Dime,Quarter,
}
#[derive(Debug)]
enum CoinWithData{Penny,Nickel,Dime,Quarter(UsState),
}
#[derive(Debug)]
enum UsState{//Alabama,Alaska,// --snip--
}fn main() {//create an instance of the enumlet four = IpAddrKind::V4;let six = IpAddrKind::V6;//print the enumroute(four);route(six);route(IpAddrKind::V4);route(IpAddrKind::V6);//create an enum with datalet home = IpAddr {kind: IpAddrKind::V4,address: String::from("127.0.0.1"),};println!("home: {:?}", home);println!("kind: {:?}", home.kind);println!("address: {:?}", home.address);let q = Message::Quit;let m = Message::Move{x: 1, y: 2};let w = Message::Write(String::from("hello"));let c = Message::ChangeColor(1, 2, 3);q.call();m.call();w.call();c.call();//print m.x + m.yif let Message::Move{x, y} = m{println!("x + y = {}", x + y);}//option enumlet some_number = Some(5);let some_string = Some("a string");let absent_number: Option<i32> = None;println!("some_number: {:?}", some_number);println!("some_string: {:?}", some_string);println!("absent_number: {:?}", absent_number);let six = plus_one(some_number);let none = plus_one(absent_number);println!("six: {:?}", six);println!("none: {:?}", none);//matchlet coin_1 = Coin::Penny;let coin_5 = Coin::Nickel;let coin_10 = Coin::Dime;let coin_25 = Coin::Quarter;println!("coin_1: {:?}", coin_1);println!("coin_5: {:?}", coin_5);println!("coin_10: {:?}", coin_10);println!("coin_25: {:?}", coin_25);let datacoin_1 = CoinWithData::Penny;let datacon_5 = CoinWithData::Nickel;let datacoin_10 = CoinWithData::Dime;let datacoin_25 = CoinWithData::Quarter(UsState::Alaska);println!("datacoin_1: {:?}", datacoin_1);println!("datacon_5: {:?}", datacon_5);println!("datacoin_10: {:?}", datacoin_10);println!("datacoin_25: {:?}", datacoin_25);value_in_cents(coin_1);value_in_cents_binding_value(datacoin_25);let v = Some(7u8);match v {Some(1) => println!("one"),Some(3) => println!("three"),Some(5) => println!("five"),Some(7) => println!("seven"),_ => println!("anything"),//default};//if letif let Some(3) = v {println!("three");}else{println!("anything");}}fn route(ip_kind: IpAddrKind) {println!("ip_kind: {:?}", ip_kind);
}fn value_in_cents(coin: Coin) -> u32{match coin{Coin::Penny => {println!("Lucky penny!");1},Coin::Nickel => 5,Coin::Dime => 10,Coin::Quarter => 25,}
}fn value_in_cents_binding_value(coin: CoinWithData) -> u32{match coin{CoinWithData::Penny => {println!("Lucky penny!");1},CoinWithData::Nickel => 5,CoinWithData::Dime => 10,//Coin::Quarter => 25,CoinWithData::Quarter(state) => {println!("State quarter from {:?}!", state);25},}
}fn plus_one(x: Option<i32>) -> Option<i32>{match x{ //match is exhaustiveNone => None,Some(i) => Some(i + 1),}
}