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Rust iter＆ match

2022-07-15 21:00:00 【51CTO】

文章目录

一、迭代器
二、match匹配

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"]
      
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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
      
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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),
       
    }
       
}
      
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