Rust iter& match

文章目录

一、迭代器

关于更多详情查看​​【标准库】​​

fn main() {
    // iter - 在每次迭代中借用集合中的一个元素
    let names = vec!["zhangsan", "lisi","wangwu","zhaoliu"];
    for name in names.iter(){
        match name{
            &"zhangsan" => println!("The people is zhangsan"),
            _ => println!("Hello:{}",name),
        }
    }


    //into_iter - 获取遍历元素所有权，会消耗集合
    let names_2 = vec!["zhangsan", "lisi","wangwu","zhaoliu"];
    for name in names_2.into_iter(){
        match name {
            "zhangsan" => println!("The people is zhangsan"),
            _ => println!("Hello:{}",name),
        }
    }


    //iter_mut - 可变地（mutably）借用集合中的每个元素，从而允许集合被就地修改。
    let mut names_3 = vec!["zhangsan", "lisi","wangwu","zhaoliu"];
    for name in names_3.iter_mut(){
        *name = match name {
            &mut "zhangsan" => "The people is zhangsan",
            _ => "other people",
        }
    }
    println!("names_3:{:?}",names_3);
    
}

// The people is zhangsan
// Hello:lisi
// Hello:wangwu
// Hello:zhaoliu

// The people is zhangsan
// Hello:lisi
// Hello:wangwu
// Hello:zhaoliu

// names_3:["The people is zhangsan", "other people", "other people", "other people"]

二、match匹配

更好的match详解：​​https://zhuanlan.zhihu.com/p/126369292​​​ 关于更多详情查看​​【标准库】​​

fn main() {
    let pair = (0,-2);
    match pair {
        (x, 0) => println!("The first  number is {}",x),
        (0, y) => println!("The second number is {}",y),
        _ => println!("It doesn't match")

    }


    let number = 13;
    match number {
        1 => println!("This number is 1"),
        2|3|4|5 => println!("This number is 2|3|4|5"),
        6...13 => println!("This number is 6..13"),    // 范围：[6,13)
        13 => println!("13 OK !!!"),
        _ => println!("other error"),
    }


    let tshirt_width = 20;
    let tshirt_size = match tshirt_width {
        16 => "S",         // 16
        17 | 18 => "M",    // 17 or 18
        19...21 => "L",    // 19 to 21; 范围：[19,21)  展开=>(19,20)
        21..=24 => "xL",   // 21 to 24; 范围：[21,24]  展开=>(21,22,23,24)
        25 => "XXL",
        _ => "Not Available",
    };
    println!("tshirt_size = {}",tshirt_size);
}

// The second number is -2
// This number is 6..13
// tshirt_size = L

匹配与解构

age()->u8{
    15
}

fn main() {
    // 引用解构一：
    let ref_01 = &12;
    match ref_01{
        &val =>println!("Got a value is {}",val),
    }

    // 引用解构二：
    match *ref_01{
        val =>println!("Got a value is {}",val),
    }

    // 引用解构三：
    let mut ref_02 = 12;
    match ref_02{
        ref mut val =>{
            *val +=12;
            println!("修改了变量的值后：{}",val)
        }
    }

    // match 条件匹配
    let pair = (2,-12);
    match pair {
        (x,y) if x == y =>println!(" These are twins !"),
        (x,y) if x+y ==-10 =>println!("两个数值相差10！"),
        (x,_) if 1 == x%2 =>println!("x是奇数！"),
        _ =>println!("No match found!"),
    }

    match age(){
        0 => println!("age error!"),
        n@1...13 =>println!("I'm a child of age {:?}",n),
        n@13...19=>println!("I'm a teen of age {:?}",n),
        n =>println!("I'm an old person of age {:?}",n),
    }
}