Rust语言精要

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

❯ rustup showDefault host: x86_64-apple-darwinrustup home:  /Users/yuchanns/.rustupstable-x86_64-apple-darwin (default)rustc 1.49.0 (e1884a8e3 2020-12-29)❯ ls /Users/yuchanns/.rustupsettings.toml toolchains    update-hashes❯ ls /Users/yuchanns/.rustup/toolchainsstable-x86_64-apple-darwin❯ ls /Users/yuchanns/.rustup/toolchains/stable-x86_64-apple-darwinbin   etc   lib   share❯ ls /Users/yuchanns/.rustup/toolchains/stable-x86_64-apple-darwin/bincargo         cargo-clippy  cargo-fmt     clippy-driver rust-gdb      rust-gdbgui   rust-lldb     rustc         rustdoc       rustfmt

❯ cargo new proj_name     Created binary (application) `proj_name` package❯ tree proj_nameproj_name├── Cargo.toml└── src    └── main.rs1 directory, 2 files

❯ cd proj_name❯ cargo run .   Compiling proj_name v0.1.0 (/Users/yuchanns/Coding/backend/github/rustbyexample/trpl/proj_name)    Finished dev [unoptimized + debuginfo] target(s) in 1.02s     Running `target/debug/proj_name .`Hello, world!

❯ cat Cargo.toml[package]name = "proj_name"version = "0.1.0"authors = ["yuchanns <airamusume@gmail.com>"]edition = "2018"[dependencies]rand = "0.8.1"

cargo install cargo-editcargo add randcargo rm rand

❯ cat ~/.cargo/config[source.crates-io]registry = "https://github.com/rust-lang/crates.io-index"replace-with = 'ustc'[source.ustc]registry = "git://mirrors.ustc.edu.cn/crates.io-index"

fn main() {    let a = {        let a = 1;        let b = 2;        a + b // 注意这里没有;会直接返回求值结果    };    println!("a: {}", a);}

fn main () {    let a = "hello world"}

fn main () {    let mut a = "hello";    a = "world";}

fn main() {    let a = String::from("hello world");    let b = &a;    let a = String::from("hello yuchanns");    println!("a is {}, b is {}", a, *b);}

fn main () {    let a = String::from("hello world");    // 下面的表达式中位置表达式出现在值上下文(即赋值表达式的右侧)    // 将一个位置表达式赋值给另一个位置表达式，出现了所有权的转移    let b = a;    println!("b is {}", b);    // println!("a is {}", a); // 这里会编译失败，提示：a value used here after move.}

fn fizz_buzz(num: i32) -> String {    // ...}

fn main() {    // 返回值里的impl表明闭包实际上是用匿名结构体实现了一个trait    fn make_true2() -> impl Fn() -> bool {        let s = "hello world2";        // 函数作为返回值        fn is_true() -> bool {            //函数内部无法引用外部变量            // println!("s: {}", s); // can't capture dynamic environment in a fn item            true        }        fn make_true() -> fn() -> bool {            is_true        }        println!("make_true: {}", make_true()());        // 闭包作为返回值        // 使用||代替函数的()        move || -> bool {            // 闭包可以引用外部变量            // 但需要通过move显式转移所有权，代替默认的引用            println!("s: {}", s);            true        }    }    println!("make_true2: {}", make_true2()());}

fn main () {    let n = 13;    // if分支是块表达式，返回类型必须相同    let result = if (n > 10) {        true    } else {        false    };    println!("result: {}", result);    for n in 1..10 {        println!("now n is {}", n);    }    fn while_true() -> i32 {        while true {            return 10; // 编译器忽略内部会返回i32，因为认为while条件有真有假，不会一直为true        }        return 11; // 如果省略这一行，编译器会认为函数最终返回了一个单元值()    }    println!("while_true: {}", while_true());}

fn main() {    let number = 42;    match number {        0 => println!("zero"),        n @ 42 => println!("value is {}", n),        _ => println!("rest of all"),    }    let mut v = vec![1, 2, 3, 4];    while let Some(x) = v.pop() {        println!("{}", x);    }}

struct People {    name: &'static str,    gender: u32,}impl People {    fn new(name: &'static str, gender: u32) -> Self {        return People{name: name, gender: gender};    }    // 自身需要mut    fn set_name(&mut self, name: &'static str) {        self.name = name;    }    fn name(&self) {        println!("name: {:?}", self.name);    }    fn gender(&self) {        let gender = if self.gender == 1 {"boy"} else {"girl"};        println!("name: {:?}", gender);    }}fn main() {    // 需要mut才能调用set_name    let mut p = People::new("yuchanns", 1);    p.name();    p.set_name("yuchanns2");    p.name();    p.gender();}

// 成员是值enum Number {    Zero,    One,    Two,}// 类C枚举enum Color {    Red = 0xff0000,    Green = 0x00ff00,    Blue = 0x0000ff,}// 携带类型参数enum IpAddr {    V4(u8, u8, u8, u8),    V6(String),}fn main() {    // 调用    let a = Number::One;    match a {        Number::Zero => println!("0"),        Number::One => println!("1"),        Number::Two => println!("2"),    }}

struct Plane;struct Car;trait Behave {    fn behave(&self);}impl Behave for Plane {    fn behave(&self) {        println!("plane move by fly");    }}impl Behave for Car {    fn behave(&self) {        println!("car move by wheels");    }}// 泛型结合trait限定行为fn behave_static<T: Behave>(s: T) {    s.behave();}fn behave_dyn(s: &dyn Behave) {    s.behave();}fn main() {    let plane = Plane;    // 静态分发，编译时展开，无运行时开销    behave_static::<Plane>(plane);    // 动态分发，有运行时开销    behave_dyn(&Car);}

enum Result<T, E> {    Ok(T),    Err(E),}

use rand::Rng;use std::cmp::Ordering;use std::io::stdin;fn main() {    println!("Guess the number!");    let secret_number = rand::thread_rng().gen_range(1..101);    loop {        println!("Please input your guess:");        let mut guess = String::new();        stdin().read_line(&mut guess).expect("Failed to read line");        // Result是个枚举        // 可以通过match Result进行成功或失败的处理        let guess: u32 = match guess.trim().parse() {            Ok(num) => num,            Err(_) => {                // 失败的时候跳过当次循环                println!("Please type a number!");                continue;            }        };        println!("Your guessed: {}", guess);        match guess.cmp(&secret_number) {            Ordering::Less => println!("Too small!"),            Ordering::Greater => println!("Too big!"),            Ordering::Equal => {                println!("You win!");                break;            }        }    }}