Rust 备忘清单

查看: Rust 类型

// 打印输出
print!("Hello World\n");
// 打印后追加新行
println!("追加新行");
// 打印为错误
eprint!("这是一个错误\n");
// 打印为新行错误
eprintln!("这是新行的错误");

// 初始化和声明变量
let some_variable = "This_is_a_variable";
// 使变量可变
let mut mutable_variable = "Mutable";
// 分配多个变量
let (name, age) = ("ElementalX", 20);
// （全局）常量
const SCREAMING_SNAKE_CASE:i64 = 9;

// 行注释
/*.............块注释 */
/// 外部文档注释
//! 内部文档评论

另见: 注释 (doc.rust-lang.org)

fn test(){
  println!("这是一个函数!");
}
fn main(){
  test();
}

查看: Functions

macro_rules! foo {
  ($l:tt) => { bar!($l); }
}
macro_rules! bar {
  (3) => {}
}
foo!(3);

struct Point { x: i32, y: i32 }
let p = Point { x: 10, y: 11 };
let px: i32 = p.x;

结构体是一个使用关键字 struct 定义的标称型(nominal)结构体类型

enum Foo {
  Bar,       // 0
  Baz = 123, // 123
  Quux,      // 124
}

let baz_discriminant = Foo::Baz as u32;
assert_eq!(baz_discriminant, 123);

type Point = (u8, u8);
let p: Point = (41, 68);

let mut a: u32 = 8;
let b: u64 = 877;
let c: i64 = 8999;
let d = -90;

let mut sixty_bit_float: f64 = 89.90;
let thirty_two_bit_float: f32 = 7.90;
let just_a_float = 69.69;

let true_val: bool = true;
let false_val: bool = false;
let just_a_bool = true;
let is_true = 8 < 5;  // => false

let first_letter_of_alphabet = 'a';
let explicit_char: char = 'F';
let implicit_char = '8';
let emoji = "\u{1f600}";   // => 😀

let community_name = "AXIAL";
let no_of_members: &str = "ten";
println!("社区的名称是 {community_name}，它有 {no_of_members} 个成员");

查看: 字符串

┌─────┬─────┬─────┬─────┬─────┬─────┐
| 92  | 97  | 98  | 99  | 98  | 94  |
└─────┴─────┴─────┴─────┴─────┴─────┘
   0     1     2     3     4     5

let array: [i64; 6] = [92,97,98,99,98,94];

let mut array: [i32 ; 3] = [2,6,10];
array[1] = 4;
array[2] = 6;

使用 mut 关键字使其可变

let mut array: [ i64; 4] = [1,2,3,4];
// 下限包括在内，上限不包括在内
let mut slices: &[i64] = &array[0..3]
println!("切片的元素是：{slices:?}");

let some_vector = vec![1,2,3,4,5]; 

使用 vec! 宏声明向量

let tuple = (1, 'A' , "Cool", 78, true);

let cs:&str = "备忘清单";
// => 为开发者分享备忘单
println!("为开发者分享 {cs}");

// 创建一个空字符串对象
let my_string = String::new;
// 转换为字符串对象
let S_string = a_string.to_string()
// 创建一个初始化的字符串对象
let lang = String::from("Rust");  
println!("First language is {lang}");

let rand = String::from("Random String");
rand.capacity()  // => 13

以字节为单位计算字符串的容量

let name = String::from("ElementalX");
name.contains("Element") // => true

检查子字符串是否包含在原始字符串中

let mut half_text = String::from("Hal");
half_text.push('f');    // => Half

let mut hi = String::from("Hey there...");
hi.push_str("How are you doing??");
// => Hey there...How are you doing??
println!("{hi}");

let (e, f) = (1, 100);
let greater = f > e;        // => true
let less = f < e;           // => false
let greater_equal = f >= e; // => true
let less_equal = e <= f;    // => true
let equal_to = e == f;      // => false
let not_equal_to = e != f;  // => true

let (a, b) = (4, 5);
let sum: i32 = a + b;            // => 9
let subtractions: i32 = a - b;   // => -1
let multiplication: i32 = a * b; // => 20
let division: i32 = a / b;       // => 0
let modulus: i32 = a % b;        // => 4

let (g, h) = (0x1, 0x2);
let bitwise_and = g & h;  // => 0
let bitwise_or = g | h;   // => 3
let bitwise_xor = g ^ h;  // => 3
let right_shift = g >> 2; // => 0
let left_shift = h << 4;  // => 32 

let (c, d) = (true, false);
let and = c && d;  // => false
let or  = c || d;  // => true
let not = !c;      // => false

let mut k = 9;
let mut l = k;

let case1: i32 = 81;
let case2: i32 = 82;
if case1 < case2 {
  println!("case1 大于 case2");
}

let case3 = 8;
let case4 = 9;
if case3 >= case4 {
  println!("case3 优于 case4");
} else {
  println!("case4 大于 case3");
}

let foo = 12;
let bar = 13;
if foo == bar {
  println!("foo 等于 bar");
} else if foo < bar {
  println!("foo 小于 bar");
} else if foo != bar {
  println!("foo 不等于 bar");
} else {
  println!("Nothing");
}

let nested_conditions = 89;
if nested_conditions == 89 {
    let just_a_value = 98;
    if just_a_value >= 97 {
        println!("大于 97");
    }
}

for mut i in 0..15 {
  i-=1;
  println!("i 的值为：{i}");
}

let mut check =  0;
while check < 11{
  println!("check 是：{check}");
  check+=1;
  println!("递增后：{check}");
  if check == 10{
    break; // 停止 while
  }
}

loop {
  println!("你好，世界永远！");
}

无限循环表示

let mut i = 1;
loop {
  println!("i 是 {i}");
  if i > 100 {
    break;
  }
  i *= 2;
}

for (v, c) in (0..10+1).enumerate(){
  println!("{c} 数字循环");
  if v == 9{
    println!("我们继续？");
    continue;
  }
  println!{"v 的值为：{v}"};
}

fn print_message(){
  println!("Hello, Quick Reference!");
}
fn main(){
  // 在 Rust 中调用函数
  print_message();
}

fn main()
{
  let x:u32 = 10;
  let y:u32 = 20;
  
  // => 200
  println!("计算: {}", cal_rect(x, y));
}
fn cal_rect(x:u32, y:u32) -> u32
{
  x * y
}

fn main(){
  let mut by_ref = 3;      // => 3
  power_of_three(&mut by_ref);
  println!("{by_ref}");  // => 9
}
fn power_of_three(by_ref: &mut i32){
  // 取消引用很重要
  *by_ref = *by_ref * *by_ref;
  println!("{by_ref}");  // => 9
}

fn main(){
  let (mut radius, mut pi) = (3.0, 3.14);
  let(area, _perimeter) = calculate (
      &mut radius,
      &mut pi
  );
  println!("圆的面积和周长为：{area} & {_perimeter}");
}
fn calculate(radius : &mut f64, pi: &mut f64) -> (f64, f64){
  let perimeter = 2.0 * *pi * *radius;
  let area = *pi * *radius * *radius;
  return (area, perimeter);
}

fn main(){
  let mut array: [i32 ; 5] = [1,2,3,4,6];
  print_arrays(array);
  println!("元素：{array:?}");
}
fn print_arrays(mut array:[i32; 5]) {
  array[0] = 89;
  array[1] = 90;
  array[2] = 91;
  array[3] = 92;
  array[4] = 93;
  println!("元素：{array:?}");
}

fn main(){
  let mut arr:[i32; 5] = [2,4,6,8,10];
  multiply(arr);
  println!("数组是：{:?}", multiply(arr));
}
fn multiply (mut arr: [i32 ; 5]) -> [i32 ; 5]{
  arr[2] = 90;
  for mut i in 0..5 {
      arr[i] = arr[i] * arr[2];
  }
  return arr;
}

use std::fmt::Debug;
fn foo<T>(x: &[T]) where T: Debug {
    // 省略细节
}
foo(&[1, 2]);

let a_int = 90; // int
// int 到 float
let mut type_cast = (a_int as f64);

let orginal: char = 'I';
// char 到 int => 73
let type_casted: i64 = orginal as i64;

要在 Rust 中执行类型转换，必须使用 as 关键字

let mut foo = 4;
let mut borrowed_foo = &foo;
println!("{borrowed_foo}");

let mut bar = 3;
let mut mutable_borrowed_bar = &mut bar;
println!("{mutable_borrowed_bar}");

这里借用的值使用 & 运算符从值一中借用值

let mut borrow = 10;
let deref = &mut borrow;
println!("{}", *deref);

可以使用 * 操作符在 rust 中取消引用

{
  // 范围仅限于此大括号
  let a_number = 1;
}
println!("{a_number}");

这将产生错误，因为变量 a_number 的范围在大括号处结束