RUST学习1

运行命令

cargo doc --open
rustup doc
cargo new --vcs=git
cargo build
cargo run
cargo check 更快编译，但不生成可执行文件
cargo build --release 生成的执行文件运行更快
benchmark基准测试

Variables and Mutability
mutable 易变的

let mut x=5

rust默认变量不可变

fn main() {
const MAX_POINTS: u32 = 100_000;
}
const 整个运行时间都存在

fn main() {
let spaces = “ “;
let spaces = spaces.len();
}

Data Types

interger 默认i32
float 默认 f64
char ‘’ 4字节*Accented letters; Chinese, Japanese, and Korean characters; emoji; and zero-width spaces are all valid char values in Rust. *
string “”

tuple 元组 固定 类型可以不同

fn main() {
    let tup: (i32, f64, u8) = (500, 6.4, 1);
}
fn main() {
    let x: (i32, f64, u8) = (500, 6.4, 1);

    let five_hundred = x.0;

    let six_point_four = x.1;

    let one = x.2;
}

array 数组 类型相同 固定 存在栈中

fn main() {
    let a = [1, 2, 3, 4, 5];
}

fn main() {
let months = ["January", "February", "March", "April", "May", "June", "July",
              "August", "September", "October", "November", "December"];
}

fn main() {
let a: [i32; 5] = [1, 2, 3, 4, 5];
}


fn main() {
let a = [3; 5];
}
let first = a[0];

rust会检查索引跃出

vector 不固定

Functions

fn main() {
    println!("Hello, world!");

    another_function();
}

fn another_function() {
    println!("Another function.");
}

Rustdoesn’t carewhere you define your functions, only that they’re defined somewhere.

fn main() {
    another_function(5, 6);
}


fn another_function(x: i32, y: i32) {
    println!("The value of x is: {}", x);
    println!("The value of y is: {}", y);
}

必须声明参数类型

---

Statementsare instructions that perform some action and do not return a value.
let y = 6; 无返回值不能赋给其他变量
Expressions evaluate to a resulting value.

fn main() {
    let x = 5;

    let y = {
        let x = 3;
        x + 1
    };

    println!("The value of y is: {}", y);
}

Note the x + 1 line without a semicolon at the end, which is unlike most of the lines you’ve seen so far. Expressions do not include ending semicolons. If you add a semicolon to the end of an expression, you turn it into a statement, which will then not return a value.

返回值

fn five() -> i32 {
    5
}

fn main() {
    let x = five();

    println!("The value of x is: {}", x);
}

fn main() {
    let x = plus_one(5);

    println!("The value of x is: {}", x);
}

fn plus_one(x: i32) -> i32 {
    x + 1;
}

Comments

//

control

fn main() {
    let number = 3;

    if number < 5 {
        println!("condition was true");
    } else {
        println!("condition was false");
    }
}

Rust will not automatically try to convert non-Boolean types to a Boolean

fn main() {
    let number = 6;

    if number % 4 == 0 {
        println!("number is divisible by 4");
    } else if number % 3 == 0 {
        println!("number is divisible by 3");
    } else if number % 2 == 0 {
        println!("number is divisible by 2");
    } else {
        println!("number is not divisible by 4, 3, or 2");
    }
}

fn main() {
    let condition = true;
    let number = if condition { 5 } else { 6 };

    println!("The value of number is: {}", number);
}

循环

fn main() {
    loop {
        println!("again!");
    }
}

fn main() {
    let mut counter = 0;

    let result = loop {
        counter += 1;

        if counter == 10 {
            break counter * 2;
        }
    };

    println!("The result is {}", result);
}

while

fn main() {
    let mut number = 3;

    while number != 0 {
        println!("{}!", number);

        number -= 1;
    }

    println!("LIFTOFF!!!");
}

for

use a for loop and execute some code for each item in a collection

fn main() {
    let a = [10, 20, 30, 40, 50];

    for element in a.iter() {
        println!("the value is: {}", element);
    }
}

fn main() {
    for number in (1..4).rev() {
        println!("{}!", number);
    }
    println!("LIFTOFF!!!");
}

rev, to reverse the range

guess game . example

fn main() {
let x = 5;
let y = 10;

println!("x = {} and y = {}", x, y);
}

cargo doc --open

The** trim **method on a String instance will eliminate any whitespace at the beginning and end
5\n 变成 5
The **parse **method on strings parses a string into some kind of number.

cargo fmt 自动调整格式
https://github.com/rust-lang/rustfmt