feat: finish more rustlings

rustlings/exercises/primitive_types/primitive_types1.rs

@@ -2,7 +2,7 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
+// 好
 
 fn main() {
     // Booleans (`bool`)
@@ -12,7 +12,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = true; // Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }

rustlings/exercises/primitive_types/primitive_types2.rs

@@ -2,7 +2,7 @@
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
-// I AM NOT DONE
+// 单引号字符, 双引号字符串.
 
 fn main() {
     // Characters (`char`)
@@ -16,7 +16,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = '!'; // Finish this line like the example! What's your favorite character?
     // Try a letter, try a number, try a special character, try a character
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {

rustlings/exercises/primitive_types/primitive_types3.rs

@@ -2,10 +2,11 @@
 // Create an array with at least 100 elements in it where the ??? is. 
 // Execute `rustlings hint primitive_types3` for hints!
 
-// I AM NOT DONE
+// 什么时候 JS 能有这么方便 Range 类型.
 
 fn main() {
-    let a = ???
+    // 1 到 100
+    let a = [1..100];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");

rustlings/exercises/primitive_types/primitive_types4.rs

@@ -2,13 +2,14 @@
 // Get a slice out of Array a where the ??? is so that the test passes.
 // Execute `rustlings hint primitive_types4` for hints!!
 
-// I AM NOT DONE
+// 数组切片前要先借值.
 
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    // 从 1 到 3, 不包括 4.
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }

rustlings/exercises/primitive_types/primitive_types5.rs

@@ -2,11 +2,11 @@
 // Destructure the `cat` tuple so that the println will work.
 // Execute `rustlings hint primitive_types5` for hints!
 
-// I AM NOT DONE
+// Tuple 比数组语义更清晰.
 
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }

rustlings/exercises/primitive_types/primitive_types6.rs

@@ -3,9 +3,9 @@
 // You can put this right into the `println!` where the ??? is.
 // Execute `rustlings hint primitive_types6` for hints!
 
-// I AM NOT DONE
+// Tuple 的下标是属性
 
 fn main() {
     let numbers = (1, 2, 3);
-    println!("The second number is {}", ???);
+    println!("The second number is {}", numbers.1);
 }

rustlings/exercises/quiz1.rs

@@ -7,10 +7,16 @@
 // more than 40 at once, each apple only costs 1! Write a function that calculates
 // the price of an order of apples given the order amount. No hints this time!
 
-// I AM NOT DONE
+// 来一箱苹果
 
 // Put your function here!
-// fn ..... {
+fn calculate_apple_price(count: i32) -> i32 {
+    if (count <= 40) {
+        count * 2
+    } else {
+        count
+    }
+}
 
 // Don't modify this function!
 #[test]

rustlings/exercises/quiz2.rs

@@ -7,7 +7,7 @@
 // you think each value is. That is, add either `string_slice` or `string`
 // before the parentheses on each line. If you're right, it will compile!
 
-// I AM NOT DONE
+// 要记住标准库方法的返回值类型才行.
 
 fn string_slice(arg: &str) {
     println!("{}", arg);
@@ -17,14 +17,15 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ("blue");
-    ("red".to_string());
-    (String::from("hi"));
-    ("rust is fun!".to_owned());
-    ("nice weather".into());
-    (format!("Interpolation {}", "Station"));
-    (&String::from("abc")[0..1]);
-    ("  hello there ".trim());
-    ("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string_slice("nice weather".into());
+    string("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }

rustlings/exercises/strings/strings1.rs

@@ -2,13 +2,39 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings1` for hints ;)
 
-// I AM NOT DONE
+// 多种写法
 
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    // 从 str 到 String 的多种写法
+
+    // 1. 初始化
+    // String::from("blue")
+
+    // 2. Display::to_string
+    // "blue".to_string()
+
+    // 3. std::borrow::ToOwned
+    // "blue".to_owned()
+
+    // 4. 根据类型自动判断, 此处是函数的返回值 String
+    // "blue".into()
+
+    // 5. 格式化
+    // format!("blue")
+
+    /*
+     * 就目前官方文档和社区讨论来看:
+     * 应该优先选择 1 和 2.
+     * 事实上 2 等于 1 等于 3.
+     * 4 取决于上下文
+     * 5 是调用 2 的宏.
+     * 综上所述, 考虑到简洁, 以及与其他类型转化成 String 的一致性, 首选 2.
+     * 如果值用于不同函数, 参数类型不定, 4 会很方便.
+     */
+    "blue".to_string()
 }

rustlings/exercises/strings/strings2.rs

@@ -2,11 +2,11 @@
 // Make me compile without changing the function signature!
 // Execute `rustlings hint strings2` for hints :)
 
-// I AM NOT DONE
+// 引用 String 会变成切片
 
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");

rustlings/exercises/structs/structs1.rs

@@ -1,14 +1,19 @@
 // structs1.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
+// 结构拥有数据, 所以结构里不能使用 &str.
 
+// 传统结构
 struct ColorClassicStruct {
     // TODO: Something goes here
+    name: String,
+    hex: String,
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+// 元组结构
+struct ColorTupleStruct(/* TODO: Something goes here */ String, String);
 
+// 单元结构
 #[derive(Debug)]
 struct UnitStruct;
 
@@ -19,7 +24,10 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct {
+            name: "green".to_string(),
+            hex: "#00FF00".to_string(),
+        };
 
         assert_eq!(green.name, "green");
         assert_eq!(green.hex, "#00FF00");
@@ -28,7 +36,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct("green".to_string(), "#00FF00".to_string());
 
         assert_eq!(green.0, "green");
         assert_eq!(green.1, "#00FF00");
@@ -37,7 +45,7 @@ mod tests {
     #[test]
     fn unit_structs() {
         // TODO: Instantiate a unit struct!
-        // let unit_struct =
+        let unit_struct = UnitStruct;
         let message = format!("{:?}s are fun!", unit_struct);
 
         assert_eq!(message, "UnitStructs are fun!");

rustlings/exercises/structs/structs2.rs

@@ -1,7 +1,7 @@
 // structs2.rs
 // Address all the TODOs to make the tests pass!
 
-// I AM NOT DONE
+// 复制结构时, 合并原结构的语法是两个点开头, 而且必须放在最后, 没有逗号结尾. 虽然放在最后, 但会跳过已经明确指定的字段.
 
 #[derive(Debug)]
 struct Order {
@@ -12,6 +12,8 @@ struct Order {
     made_by_email: bool,
     item_number: u32,
     count: u32,
+
+
 }
 
 fn create_order_template() -> Order {
@@ -34,7 +36,13 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = Order {
+            name: "Hacker in Rust".to_string(),
+            count: 1,
+            ..order_template
+        };
+
+
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);

rustlings/exercises/structs/structs3.rs

@@ -3,7 +3,7 @@
 // exercise we have defined the Package struct and we want to test some logic attached to it,
 // make the code compile and the tests pass! If you have issues execute `rustlings hint structs3`
 
-// I AM NOT DONE
+// 在结构基础上实现方法, 模仿类.
 
 #[derive(Debug)]
 struct Package {
@@ -16,17 +16,24 @@ impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
         if weight_in_grams <= 0 {
             // Something goes here...
+            panic!("Invalid weight")
         } else {
-            return Package {sender_country, recipient_country, weight_in_grams};
+            return Package {
+                sender_country,
+                recipient_country,
+                weight_in_grams,
+            };
         }
     }
 
-    fn is_international(&self) -> ??? {
+    fn is_international(&self) -> bool {
         // Something goes here...
+        self.sender_country != self.recipient_country
     }
 
-    fn get_fees(&self, cents_per_kg: i32) -> ??? {
+    fn get_fees(&self, cents_per_kg: i32) -> i32 {
         // Something goes here... (beware of grams to kg conversion)
+        self.weight_in_grams * cents_per_kg / 1000
     }
 }
 
@@ -47,7 +54,6 @@ mod tests {
     fn create_international_package() {
         let sender_country = String::from("Spain");
         let recipient_country = String::from("Russia");
-
         let package = Package::new(sender_country, recipient_country, 1200);
 
         assert!(package.is_international());
@@ -58,10 +64,8 @@ mod tests {
         let sender_country = String::from("Spain");
         let recipient_country = String::from("Spain");
 
-        let cents_per_kg = ???;
-
+        let cents_per_kg = 3000;
         let package = Package::new(sender_country, recipient_country, 1500);
-
         assert_eq!(package.get_fees(cents_per_kg), 4500);
     }
 }