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p18.match/match_learn/.gitignore

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+/target

p18.match/match_learn/Cargo.toml

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+[package]
+name = "match_learn"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

p18.match/match_learn/src/main.rs

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+use std::{env::var, sync::atomic::AtomicI32, vec};
+
+fn main() {
+    println!("Hello, world!");
+    learn();
+}
+
+struct Point {
+    x: i32,
+    y: i32,
+}
+fn learn() {
+    let var = 3;
+    match var {
+        //@绑定val，使用..匹配一些值
+        val @ 1..=4 => println!("match 1..4, {}", val),
+        _ => println!("match"),
+    }
+
+    let mut var = vec![1, 2, 3, 4, 5, 6, 7];
+    while let Some(var) = var.pop() {
+        match var {
+            //@绑定val，使用|来进行多重匹配
+            val @ (1 | 3 | 5) => println!("match 1,3,5 => {}", val),
+            _ => println!("miss match val {}", var),
+        }
+    }
+
+    let mut var = vec![1, 2, 3, 4, 5, 6, 7];
+    let cond = 2;
+    while let Some(var) = var.pop() {
+        match var {
+            //使用if语句来进行进一步的限制，b不满足条件的同样会走到其他分支
+            val @ (1 | 3 | 5) if val > cond => println!("match 1,3,5 > {} => {}", cond, val),
+            val @ (1 | 3 | 5) => println!("match 1,3,5 <= {} => {}", cond, val),
+            _ => println!("aa miss match val {}", var),
+        }
+    }
+
+    let var = vec!["first", "second", "third", "fourth", "last"];
+    match var[..] {
+        [last, .., end] => println!("start str is {}, end str is {}", last, end),
+        _ => {}
+    }
+
+    let var = ("first", "second", "third", "fourth", "last");
+    // let var = ("first", "second", "third", "fourth", "end");
+    match var {
+        (last, .., "last") => println!("a str end by \"last\", start str is {}", last),
+        _ => println!("not match a tuple end with \"last\""),
+    }
+
+    //let var = (12, "string");
+    let var = (123, "string");
+    match var {
+        (x, y) if x == 12 => {
+            println!("fist is 12, second is {}", y);
+        }
+        (x, y) => {
+            println!("fist is not 12 but {}, second is {}", x, y);
+        }
+    }
+    //解构元组
+    let var = (123, "string");
+    let (x, y) = var;
+    println!("after x:{}, y{}", x, y);
+
+    //解构结构体
+    let var = Point { x: 23, y: 34 };
+    let Point { x, y } = var; //解构时成员明明必须相同
+    println!("after x:{}, y{}", x, y);
+
+    //区间匹配
+    let c = 'c';
+    match c {
+        'a'..='z' => {
+            println!("is a lower char");
+        }
+        'A'..='Z' => {
+            println!("is a upper char");
+        }
+        '0'..='9' => {
+            println!("is a number");
+        }
+        _ => {
+            println!("other char");
+        }
+    }
+    let var = Point { x: 23, y: 34 };
+    deconstruct((23, 34), ((45, 23423), var));
+
+    //可以通过元组将结构体和元组嵌套进行解构
+    //使用_开头的变量即使未使用也不会导致编译器警告。
+    let var = Point { x: 23, y: 34 };
+    let ((_w, _z), Point { x, y }) = ((12, 34), var);
+
+    //_不会绑定变量转移所有权，所以再使用_后所有权还是在原变量上
+    let var = Some(String::from("strzzzz"));
+    if let Some(_) = var {
+        println!("find a string");
+    }
+    println!("str is {:?}", var);
+}
+
+fn deconstruct((h, t): (i32, i32), ((w, r), Point { x, y }): ((i32, i32), Point)) {
+    println!("h:{},t:{}, w:{},r:{},x:{},y:{},", h, t, w, r, x, y);
+}