fix errors in enum.md

src/SUMMARY.md

@@ -19,7 +19,7 @@
   - [Enum](compound-types/enum.md)
 - [Flow Control](flow-control.md)
 - [Pattern Match todo](pattern-match/intro.md)
-  - [match, if let](pattern-match/match-iflet.md)
+  - [match, matches! and if let](pattern-match/match-iflet.md)
   - [Option destructing](pattern-match/option.md)
   - [Patterns](pattern-match/patterns.md)
 - [Method todo](method.md)

src/compound-types/enum.md

@@ -48,7 +48,7 @@ fn main() {
 } 
 ```
 
-🌟🌟🌟 we can get the data which a enum variant is holding by pattern match
+🌟🌟 we can get the data which a enum variant is holding by pattern match
 ```rust,editable
 
 // 仅填空，不要修改其它代码！
@@ -63,14 +63,14 @@ fn main() {
     let msg = Message::Move{x: 1, y: 1};
 
     if let Message::Move{__} = msg {
-        assert_eq!(x, y);
+        assert_eq!(a, b);
+    } else {
+        panic!("NEVER LET THIS RUN！");
     }
-
-    panic!("NEVER LET THIS RUN！");
 } 
 ```
 
-🌟🌟🌟 使用枚举对类型进行同一化
+🌟🌟 使用枚举对类型进行同一化
 
 ```rust,editable
 
@@ -102,7 +102,8 @@ fn show_message(msg: Message) {
 🌟🌟 As there is no `null` in Rust, we have to use enum  `Option<T>`  to deal the cases when value is absent.
 ```rust,editable
 
-// Only fill in the blanks, DON'T change other code！
+// fill in the blank to make the `println` work.
+// also add some code to prevent the `panic` from running.
 fn main() {
     let five = Some(5);
     let six = plus_one(five);
@@ -110,8 +111,8 @@ fn main() {
 
     if let __ = six {
         println!("{}", n)
-    }
-
+    } 
+        
     panic!("NEVER LET THIS RUN！");
 } 
 

src/functional-programing/iterator.md

@@ -1,5 +1,7 @@
 # Iterator
 
+https://doc.rust-lang.org/stable/rust-by-example/flow_control/for.html#for-and-iterators
+
 ```rust,editable
 // (all the type annotations are superfluous)
 // A reference to a string allocated in read only memory

src/pattern-match/intro.md

@@ -1 +1,6 @@
 # Pattern Match
+Learning resources: 
+- English: [Rust Book 18](https://doc.rust-lang.org/book/ch18-00-patterns.html)
+- 简体中文: [Rust语言圣经 - 模式匹配](https://course.rs/basic/match-pattern/intro.html)
+
+

src/pattern-match/match-iflet.md

@@ -1 +1,119 @@
 # match, if let
+
+### match
+🌟🌟
+```rust,editable
+
+// fill the blanks
+enum Direction {
+    East,
+    West,
+    North,
+    South,
+}
+
+fn main() {
+    let dire = Direction::South;
+    match dire {
+        Direction::East => println!("East"),
+        __  => { // matching South or North here
+            println!("South or North");
+        },
+        _ => println!(__),
+    };
+}
+```
+
+🌟🌟 match is an expression, so we can use it in assignments
+```rust,editable
+
+fn main() {
+    let boolean = true;
+
+    // fill the blank with an match expression:
+    //
+    // boolean = true, binary = 1
+    // boolean = false, binary = 0
+    let binary = __;
+
+    assert_eq!(binary, 1);
+}
+```
+
+🌟🌟 using match to get the data an enum variant holds
+```rust,editable
+
+// fill in the blanks
+enum Message {
+    Quit,
+    Move { x: i32, y: i32 },
+    Write(String),
+    ChangeColor(i32, i32, i32),
+}
+
+fn main() {
+    let msgs = [
+        Message::Quit,
+        Message::Move{x:1, y:3},
+        Message::ChangeColor(255,255,0)
+    ];
+
+    for msg in msgs {
+        show_message(msg)
+    }
+} 
+
+fn show_message(msg: Message) {
+    match msg {
+        __ => { // matches  Message::Move
+            assert_eq!(a, 1);
+            assert_eq!(b, 3);
+        },
+        Message::ChangeColor(_, g, b) => {
+            assert_eq!(g, __);
+            assert_eq!(b, __);
+        }
+        __ => println!("no data in these variants")
+    }
+}
+```
+
+### matches!
+[`matches!`](https://doc.rust-lang.org/stable/core/macro.matches.html) looks like `match`, but can do something different
+
+🌟🌟
+```rust,editable
+
+fn main() {
+    let alphabets = ['a', 'E', 'Z', '0', 'x', '9' , 'Y'];
+
+    // fill the blank with `matches!` to make the code work
+    for ab in alphabets {
+        assert!(__)
+    }
+} 
+```
+
+🌟🌟
+```rust,editable
+
+enum MyEnum {
+    Foo,
+    Bar
+}
+
+fn main() {
+    let mut count = 0;
+
+    let v = vec![MyEnum::Foo,MyEnum::Bar,MyEnum::Foo];
+    for e in v {
+        if e == MyEnum::Foo { // fix the error with changing only this line
+            count += 1;
+        }
+    }
+
+    assert_eq!(count, 2);
+}
+```
+
+### if let

zh-CN/src/SUMMARY.md

@@ -19,7 +19,7 @@
   - [枚举](compound-types/enum.md)
 - [流程控制](flow-control.md)
 - [模式匹配 todo](pattern-match/intro.md)
-  - [match 和 if let](pattern-match/match-iflet.md)
+  - [match, matches! 和 if let](pattern-match/match-iflet.md)
   - [解构 Option](pattern-match/option.md)
   - [模式](pattern-match/patterns.md)
 - [方法 Method todo](method.md)

zh-CN/src/compound-types/enum.md

@@ -48,7 +48,7 @@ fn main() {
 } 
 ```
 
-🌟🌟🌟 枚举成员中的值可以使用模式匹配来获取
+🌟🌟 枚举成员中的值可以使用模式匹配来获取
 ```rust,editable
 
 // 仅填空，不要修改其它代码！
@@ -63,14 +63,14 @@ fn main() {
     let msg = Message::Move{x: 1, y: 1};
 
     if let Message::Move{__} = msg {
-        assert_eq!(x, y);
+        assert_eq!(a, b);
+    } else {
+        panic!("不要让这行代码运行！");
     }
-
-    panic!("不要让这行代码运行！");
 } 
 ```
 
-🌟🌟🌟 使用枚举对类型进行同一化
+🌟🌟 使用枚举对类型进行同一化
 
 ```rust,editable
 
@@ -102,7 +102,7 @@ fn show_message(msg: Message) {
 🌟🌟 Rust 中没有 `null`，我们通过 `Option<T>` 枚举来处理值为空的情况
 ```rust,editable
 
-// 仅填空，不要修改其它代码！
+// 填空让 `println` 输出，同时添加一些代码不要让最后一行的 `panic` 执行到
 fn main() {
     let five = Some(5);
     let six = plus_one(five);
@@ -110,8 +110,8 @@ fn main() {
 
     if let __ = six {
         println!("{}", n)
-    }
-
+    } 
+        
     panic!("不要让这行代码运行！");
 } 
 

zh-CN/src/functional-programing/iterator.md

@@ -1,3 +1,2 @@
 # Iterator
 
-https://doc.rust-lang.org/stable/rust-by-example/flow_control/for.html#for-and-iterators