Rust的入门篇(下)

这篇博客是rust入门篇下

45. 生命周期注释

// 生命周期// 下面代码不能通过编译
// longer 函数取 s1 和 s2 两个字符串切片中较长的一个返回其引用值
// 返回值引用可能会返回过期的引用
// fn longer(s1: &str, s2: &str) -> &str {
//     if s2.len() > s1.len() {
//         s2
//     } else {
//         s1
//     }
// }// 生命周期注释
// &i32        // 常规引用
// &'a i32     // 含有生命周期注释的引用
// &'a mut i32 // 可变型含有生命周期注释的引用fn longer<'a>(s1:&'a str, s2:&'a str)->&'a str{if s2.len()>s1.len(){s2} else {s1}
}fn main(){let r;{let s1 = "rust";let s2 = "ecmascript";r = longer(s1, s2);println!("{} is longer", r);}}

46. 生命周期2

结构体中使用字符串切片引用

// 结构体中使用字符串切片引用fn main(){struct Str<'a>{content: &'a str}let s = Str{content: "string_slice"};println!("s.content={}", s.content);}

47. 泛型 特性 和 生命周期的综合例子

// 泛型、特性与生命周期 一起来use std::fmt::Display;fn longest_with_an_announcement<'a, T>(x: &'a str, y: &'a str, ann: T)-> &'a str where T: Display{println!("Announcement! {}", ann);if x.len() > y.len(){x} else{y}
}fn main(){let r = longest_with_an_announcement("abcd", "efg", "hello");println!("longest {}", r);
}

48. 接收命令行参数

// 接收命令行参数fn main(){let args = std::env::args();println!("{:?}", args);// Args { inner: ["target\\debug\\greeting.exe"] }// 遍历for arg in args{// target\debug\greeting.exeprintln!("{}", arg);}}

49. 从命令行传入字符串

// 命令行输入输入一些字母 IO流
use std::io::stdin;fn main(){let mut str_buf = String::new();// 从命令行输入一些字符stdin().read_line(&mut str_buf).expect("failed to read line");println!("your input line is \n{}", str_buf);}

50. 从文件读入

// 从文件读取字符
use std::fs;fn main(){let text = fs::read_to_string("d:/hello.txt").unwrap();println!("{}", text);}

51. 读取文件

整个文件一次性读取

// 从文件读取字符
use std::fs;fn main(){let content = fs::read("D:/text.txt").unwrap();println!("{:?}", content);}

52. IO流

// 流读取
use std::fs::{self, File};
use std::io::prelude::*;fn main(){let mut buffer = [0u8; 5];let mut file = fs::File::open("d:/text.txt").unwrap();file.read(&mut buffer).unwrap();println!("{:?}", buffer);file.read(&mut buffer).unwrap();println!("{:?}", buffer);}

53. 文件写入

use std::fs;fn main(){// 文件写入fs::write("d:/text.txt", "FROM RUST PROGRAM").unwrap();
}

54. 文件末尾追加字符

use std::io::prelude::*;
use std::fs::OpenOptions;fn main()->std::io::Result<()>{let mut file = OpenOptions::new().append(true).open("d:/text.txt")?;file.write(b" APPEND WORD");Ok(())
}

55. 读写方式打开文件

use std::io::prelude::*;
use std::fs::OpenOptions;fn main()->std::io::Result<()>{let mut file = OpenOptions::new().read(true).write(true).open("d:/text.txt")?;file.write(b"COVER")?;Ok(())}

56. 集合一

集合的创建

// 集合创建
fn main(){let vector: Vec<i32> = Vec::new(); // 创建类型为 i32 的空向量let vector = vec![1, 2, 4, 8]; // 通过数组创建向量}

57. 向集合添加元素

使用push添加元素

// push 添加 元素
fn main(){let mut vector = vec![1, 2, 4, 8];vector.push(16);vector.push(32);vector.push(64);println!("{:?}", vector);}

58. 在集合末尾添加一个集合

// append 添加集合
fn main(){let mut v1:Vec<i32> = vec![1, 2, 4, 8];let mut v2:Vec<i32> = vec![16, 32, 64];v1.append(&mut v2);println!("{:?}", v1);}

59. 集合遍历和取元素

fn main(){let mut v = vec![1, 2, 4, 8];// 相对安全的取值方法println!("{}", match v.get(0) {Some(value)=>value.to_string(),None=>"None".to_string()});// 下标取值let v = vec![1, 2, 4, 8];println!("{}", v[1]);// 遍历let v = vec![100, 32, 57];for i in &v{println!("{}", i);}}

60. string字符串操作

fn main(){// 新建字符串let string = String::new();// 基础类型转成字符串let ont = 1.to_string();let float = 1.3.to_string();let slice = "slice".to_string();//  包含 UTF-8 字符的字符串let hello = String::from("السلام عليكم");let hello = String::from("Dobrý den");let hello = String::from("Hello");let hello = String::from("שָׁלוֹם");let hello = String::from("नमस्ते");let hello = String::from("こんにちは");let hello = String::from("안녕하세요");let hello = String::from("你好");let hello = String::from("Olá");let hello = String::from("Здравствуйте");let hello = String::from("Hola");// 字符串追加let mut s = String::from("run");s.push_str("oob");s.push_str("!");// + 拼接字符串let s1 = String::from("Hello, ");let s2 = String::from("world!");let s3 = s1 + &s2;// 使用format!宏let s1 = String::from("tic");let s2 = String::from("tac");let s3 = String::from("toe");let s = format!("{}-{}-{}", s1, s2, s3);let s = "hello";let len = s.len();// 中文字符长度let s = "你好";let len = s.len(); // 6 中文utf-8编码，一个字长3个字节println!("{}", len);// 中文字符正确长度let s = "你好";let len = s.chars().count(); // 2println!("{}", len);// 字符串遍历let s = String::from("hello中文");for c in s.chars(){println!("{}", c);}// 取单个字符let s = String::from("EN中文");let a = s.chars().nth(2); // Some('中')println!("{:?}", a); // 按索引截取字符串 不推荐 遇到中文有问题let s = String::from("EN中文"); let sub = &s[0..2]; // EN// let sub = &s[0..3]; // 报错了println!("{}", sub);}

61. hashmap

use std::collections::HashMap;fn main(){// 映射表操作let mut map = HashMap::new();map.insert("color", "red");map.insert("size", "10 m^2");println!("{}", map.get("color").unwrap());// 遍历映射表操作for p in map.iter(){println!("{:?}", p);/*("color", "red")("size", "10 m^2")*/}// 先判断key是否存在，然后才安全插入map.entry("color").or_insert("red");let mut map = HashMap::new();map.insert(1, "a");// 在已经确定有某个键的情况下直接修改对应的值if let Some(x) = map.get_mut(&1){*x = "b";}for p in map.iter(){println!("{:?}", p);}// (1, "b")}

62. 面向对象

second.rs

pub struct ClassName{field: i32,
}impl ClassName{pub fn new(value: i32)->ClassName{ClassName{field: value}}pub fn public_method(&self){println!("from public method");self.private_method();}fn private_method(&self){println!("from private method");}}

main.rs

mod second;
use second::ClassName;fn main(){let object = ClassName::new(1024);object.public_method();}

63. 并发编程1

use std::thread;
use std::time::Duration;fn spawn_function(){for i in 0..5{println!("spawned thread print {}", i);thread::sleep(Duration::from_millis(1));}
}fn main(){thread::spawn(spawn_function);for i in 0..3{println!("main thread print {}", i);thread::sleep(Duration::from_millis(1));}
}

64. 并发编程2 匿名函数

use std::thread;
use std::time::Duration;fn main(){// 闭包是可以保存进变量或作为参数传递给其他函数的匿名函数。闭包相当于 Rust 中的 Lambda 表达式，格式如下：/**|参数1, 参数2, ...| -> 返回值类型 {// 函数体}*/thread::spawn(||{for i in 0..5 {println!("spawned thread print {}", i);thread::sleep(Duration::from_millis(1));}});for i in 0..3 {println!("main thread print {}", i);thread::sleep(Duration::from_millis(1));}}

65. 匿名函数与参数传递

fn main(){// 匿名函数与参数传递let inc = |num: i32|->i32{num + 1};println!("inc(5) = {}", inc(5));let inc = |num|{num + 1};println!("inc(5) = {}", inc(5));}

66. 守护线程

use std::thread;
use std::time::Duration;// join 方法可以使子线程运行结束后再停止运行程序。
fn main(){let handle = thread::spawn(||{for i in 0..5{println!("spawned thread print {}", i);thread::sleep(Duration::from_millis(1));}});for i in 0..3{println!("main thread print {}", i);thread::sleep(Duration::from_millis(1));}handle.join().unwrap();/*main thread print 0spawned thread print 0main thread print 1spawned thread print 1spawned thread print 2main thread print 2spawned thread print 3spawned thread print 4*/}

67. 使用move进行所有权迁移

使用move让子线程访问主线程变量

use std::thread;fn main() {let s = "hello";let handle = thread::spawn(move || {println!("{}", s);});handle.join().unwrap();
}

68. 主线程与子线程之间的消息收发

// 消息传递
use std::thread;
use std::sync::mpsc;fn main(){let (tx, rx) = mpsc::channel();thread::spawn(move||{let val = String::from("hi");tx.send(val).unwrap();});let received = rx.recv().unwrap();println!("Got: {}", received);}