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# ChangeLog
## 2022-03-31
- Add [Iterator](https://practice.rs/functional-programing/iterator.html)
- Add [Newtype and DST](https://practice.rs/newtype-sized.html)
## 2022-03-30
- Add [Advance Liftime](https://practice.rs/lifetime/advance.html) chapter
### 2022-03-29
- Add language switch icon in top-right corner
- Add [&'static and T: 'static](https://practice.rs/lifetime/static.html)
### 2022-03-28
- Add [Basic lifetime](https://practice.rs/lifetime/basic.html)
### 2022-03-25
- Replace gitalk with giscus comments system which is based on Github Discussions
- Update css styles
### 2022-03-24
- Add [comment-docs.md(Zh)]
### 2022-03-23
- Add [crate.md(Zh)]
- Add [module.md(Zh)]
- Add [use-pub.md(Zh)]
### 2022-03-20
- Add [Result (zh)]
- Add [Panics (Zh)]
- Add [Type conversion - others.md (zh)]
### 2022-03-18
- Add [Type conversion - From and Into( Zh )]
### 2022-03-17
- Add [Small projects with Elegant code](https://practice.rs/elegant-code-base.html)
### 2022-03-15
- Add [Formatting](https://practice.rs/formatted-output/formatting.html)
- Add [prinln! and format!](https://practice.rs/formatted-output/println.html)
- Add [Debug and Display](https://practice.rs/formatted-output/debug-display.html)
- Add [Comments and Docs](https://practice.rs/comments-docs.html)
- Add [Fighting with Compiler](https://practice.rs/fight-compiler/intro.html)
### 2022-03-14
- Add [Package and Crate](https://practice.rs/crate-module/crate.html)
- Add [Modules](https://practice.rs/crate-module/module.html)
- Add [Advanced use and pub](https://practice.rs/crate-module/use-pub.html)
### 2022-03-11
- Add one exercise in [Patterns](https://practice.rs/pattern-match/patterns.html)
- Add [Result and ?](https://practice.rs/result-panic/result.html)
### 2022-03-10
- Add [Type conversions - From/Into](https://practice.rs/type-conversions/from-into.html)
- Add [Type conversions - Others](https://practice.rs/type-conversions/others.html)
- Add [Panics](https://practice.rs/result-panic/panic.html)
- Add exercises for [diverging functions](https://practice.rs/basic-types/functions.html#diverging-functions)
### 2022-03-09
- Translate several English chapters to Chinese
- Add [Type conversions - As](https://practice.rs/type-conversions/as.html)
### 2022-03-08
- Add [HashMap](https://practice.rs/collections/hashmap.html)
- Translate several English chapters to Chinese
### 2022-03-07
- Add [Strings](https://practice.rs/collections/string.html)
- Add [Vectors](https://practice.rs/collections/vector.html)
### 2022-03-06
- Add [Advanced Traits](https://practice.rs/generics-traits/advanced-traits.html)
### 2022-03-05
- Add [Trati object](https://practice.rs/generics-traits/trait-object.html)
### 2022-03-05
- Add [Traits chapter](https://practice.rs/generics-traits/traits.html) and solutions

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<div align="center">
[![Stars Count](https://img.shields.io/github/stars/sunface/rust-by-practice?style=flat)](https://github.com/sunface/rust-by-practice/stargazers) [![Forks Count](https://img.shields.io/github/forks/sunface/rust-by-practice.svg?style=flat)](https://github.com/naaive/orange/network/members)
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[![LICENSE](https://img.shields.io/badge/license-CC_BY_4.0-green?style=flat)](https://github.com/sunface/rust-by-practice/blob/master/LICENSE)
</div>
This book was designed for easily diving into and get skilled with Rust, and it's very easy to use: All you need to do is to make each exercise compile without ERRORS and Panics !
@ -23,6 +24,45 @@ This book was designed for easily diving into and get skilled with Rust, and it'
- [https://practice.rs](https://practice.rs)
## Features
Part of our examples and exercises are borrowed from [Rust By Example](https://github.com/rust-lang/rust-by-example), thanks for your great works!
Although they are so awesome, we have our own secret weapons :)
- There are three parts in each chapter: examples, exercises and practices
- Besides examples, we have `a lot of exercises`, you can Read, Edit and Run them ONLINE
- Covering nearly all aspects of Rust, such as async/await, threads, sync primitives, optimizing, standard libraries, tool chain, data structures and algorithms etc.
- Every exercise has its own solutions
- The overall difficulties are a bit higher and from easy to super hard: easy 🌟 medium 🌟🌟 hard 🌟🌟🌟 super hard 🌟🌟🌟🌟
**What we want to do is fill in the gap between learning and getting started with real projects.**
## 🏅 Contributors
Thanks to all of our [contributors](https://github.com/sunface/rust-by-practice/graphs/contributors)!
<br />
**🏆 Special thanks to our English editor:**
<table>
<tr>
<td align="center">
<a href="https://github.com/Tanish-Eagle">
<img src="https://avatars.githubusercontent.com/u/71984506?v=4?s=100" width="160px" alt=""/>
<br />
<sub><b>Tanish-Eagle</b></sub>
</a>
</td>
</tr>
</table>
<br />
## Running locally
We use [mdbook](https://rust-lang.github.io/mdBook/) building our exercises. You can run locally with below steps:
@ -46,24 +86,6 @@ $ cd rust-by-practice && mdbook serve en/
$ cd rust-by-practice && mdbook serve zh-CN/
```
## Features
Part of our examples and exercises are borrowed from [Rust By Example](https://github.com/rust-lang/rust-by-example), thanks for your great works!
Although they are so awesome, we have our own secret weapons :)
- There are three parts in each chapter: examples, exercises and practices
- Besides examples, we have `a lot of exercises`, you can Read, Edit and Run them ONLINE
- Covering nearly all aspects of Rust, such as async/await, threads, sync primitives, optimizing, standard libraries, tool chain, data structures and algorithms etc.
- Every exercise has its own solutions
- The overall difficulties are a bit higher and from easy to super hard: easy 🌟 medium 🌟🌟 hard 🌟🌟🌟 super hard 🌟🌟🌟🌟
**What we want to do is fill in the gap between learning and getting started with real projects.**
## Some of our exercises
🌟🌟🌟 Tuple struct looks similar to tuples, it has added meaning the struct name provides but has no named fields. It's useful when you want give the whole tuple a name, but don't care the fields's names.

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30
en/src/basic-types/char-bool-unit.md
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@ -4,7 +4,7 @@
1. 🌟
```rust, editable
// make it work
// Make it work
use std::mem::size_of_val;
fn main() {
let c1 = 'a';
@ -13,14 +13,14 @@ fn main() {
let c2 = '中';
assert_eq!(size_of_val(&c2),3);
println!("Success!")
println!("Success!");
}
```
2. 🌟
```rust, editable
// make it work
// Make it work
fn main() {
let c1 = "中";
print_char(c1);
@ -35,13 +35,13 @@ fn print_char(c : char) {
3. 🌟
```rust, editable
// make println! work
// Make println! work
fn main() {
let _f: bool = false;
let t = true;
if !t {
println!("Success!")
println!("Success!");
}
}
```
@ -49,13 +49,13 @@ fn main() {
4. 🌟
```rust, editable
// make it work
// Make it work
fn main() {
let f = true;
let t = true && false;
assert_eq!(t, f);
println!("Success!")
println!("Success!");
}
```
@ -64,36 +64,36 @@ fn main() {
5. 🌟🌟
```rust,editable
// make it work, don't modify `implicitly_ret_unit` !
// Make it work, don't modify `implicitly_ret_unit` !
fn main() {
let _v: () = ();
let v = (2, 3);
assert_eq!(v, implicitly_ret_unit());
println!("Success!")
println!("Success!");
}
fn implicitly_ret_unit() {
println!("I will return a ()")
println!("I will return a ()");
}
// don't use this one
// Don't use this one
fn explicitly_ret_unit() -> () {
println!("I will return a ()")
println!("I will return a ()");
}
```
6. 🌟🌟 what's the size of the unit type?
6. 🌟🌟 What's the size of the unit type?
```rust,editable
// modify `4` in assert to make it work
// Modify `4` in assert to make it work
use std::mem::size_of_val;
fn main() {
let unit: () = ();
assert!(size_of_val(&unit) == 4);
println!("Success!")
println!("Success!");
}
```

18
en/src/basic-types/functions.md
View File

@ -3,13 +3,13 @@
```rust,editable
fn main() {
// don't modify the following two lines!
// Don't modify the following two lines!
let (x, y) = (1, 2);
let s = sum(x, y);
assert_eq!(s, 3);
println!("Success!")
println!("Success!");
}
fn sum(x, y: i32) {
@ -24,9 +24,9 @@ fn main() {
print();
}
// replace i32 with another type
// Replace i32 with another type
fn print() -> i32 {
println!("Success!")
println!("Success!");
}
```
@ -34,16 +34,16 @@ fn print() -> i32 {
3. 🌟🌟🌟
```rust,editable
// solve it in two ways
// Solve it in two ways
// DON'T let `println!` works
fn main() {
never_return();
println!("Failed!")
println!("Failed!");
}
fn never_return() -> ! {
// implement this function, don't modify the fn signatures
// Implement this function, don't modify the fn signatures
}
```
@ -90,11 +90,11 @@ fn main() {
// Diverging functions can also be used in match expression to replace a value of any value
false => {
println!("Success!");
panic!("we have no value for `false`, but we can panic")
panic!("we have no value for `false`, but we can panic");
}
};
println!("Excercise Failed if printing out this line!");
println!("Exercise Failed if printing out this line!");
}
```

46
en/src/basic-types/numbers.md
View File

@ -4,49 +4,49 @@
1. 🌟
> Tips: If we don't explicitly give one type to a varible, then the compiler will infer one for us
> Tips: If we don't explicitly assign a type to a variable, then the compiler will infer one for us.
```rust,editable
// remove something to make it work
// Remove something to make it work
fn main() {
let x: i32 = 5;
let mut y: u32 = 5;
y = x;
let z = 10; // type of z ?
let z = 10; // Type of z ?
println!("Success!")
println!("Success!");
}
```
2. 🌟
```rust,editable
// fill the blank
// Fill the blank
fn main() {
let v: u16 = 38_u8 as __;
println!("Success!")
println!("Success!");
}
```
3. 🌟🌟🌟
> Tips: If we don't explicitly give one type to a varible, then the compiler will infer one for us
> Tips: If we don't explicitly assign a type to a variable, then the compiler will infer one for us.
```rust,editable
// modify `assert_eq!` to make it work
// Modify `assert_eq!` to make it work
fn main() {
let x = 5;
assert_eq!("u32".to_string(), type_of(&x));
println!("Success!")
println!("Success!");
}
// get the type of given variable, return a string representation of the type , e.g "i8", "u8", "i32", "u32"
// Get the type of given variable, return a string representation of the type , e.g "i8", "u8", "i32", "u32"
fn type_of<T>(_: &T) -> String {
format!("{}", std::any::type_name::<T>())
}
@ -55,19 +55,19 @@ fn type_of<T>(_: &T) -> String {
4. 🌟🌟
```rust,editable
// fill the blanks to make it work
// Fill the blanks to make it work
fn main() {
assert_eq!(i8::MAX, __);
assert_eq!(u8::MAX, __);
println!("Success!")
println!("Success!");
}
```
5. 🌟🌟
```rust,editable
// fix errors and panics to make it work
// Fix errors and panics to make it work
fn main() {
let v1 = 251_u8 + 8;
let v2 = i8::checked_add(251, 8).unwrap();
@ -78,12 +78,12 @@ fn main() {
6. 🌟🌟
```rust,editable
// modify `assert!` to make it work
// Modify `assert!` to make it work
fn main() {
let v = 1_024 + 0xff + 0o77 + 0b1111_1111;
assert!(v == 1579);
println!("Success!")
println!("Success!");
}
```
@ -93,29 +93,29 @@ fn main() {
```rust,editable
// replace ? with your answer
// Replace ? with your answer
fn main() {
let x = 1_000.000_1; // ?
let y: f32 = 0.12; // f32
let z = 0.01_f64; // f64
println!("Success!")
println!("Success!");
}
```
1. 🌟🌟 make it work in two distinct ways
1. 🌟🌟 Make it work in two distinct ways
```rust,editable
fn main() {
assert!(0.1+0.2==0.3);
println!("Success!")
println!("Success!");
}
```
### Range
9. 🌟🌟 two goals: 1. modify `assert!` to make it work 2. make `println!` output: 97 - 122
9. 🌟🌟 Two goals: 1. Modify `assert!` to make it work 2. Make `println!` output: 97 - 122
```rust,editable
fn main() {
@ -135,13 +135,13 @@ fn main() {
10. 🌟🌟
```rust,editable
// fill the blanks
// Fill the blanks
use std::ops::{Range, RangeInclusive};
fn main() {
assert_eq!((1..__), Range{ start: 1, end: 5 });
assert_eq!((1..__), RangeInclusive::new(1, 5));
println!("Success!")
println!("Success!");
}
```
@ -150,7 +150,7 @@ fn main() {
11. 🌟
```rust,editable
// fill the blanks and fix the errors
// Fill the blanks and fix the errors
fn main() {
// Integer addition
assert!(1u32 + 2 == __);

8
en/src/basic-types/statements-expressions.md
View File

@ -27,7 +27,7 @@ fn main() {
### Exercises
1. 🌟🌟
```rust,editable
// make it work with two ways
// Make it work with two ways
fn main() {
let v = {
let mut x = 1;
@ -36,7 +36,7 @@ fn main() {
assert_eq!(v, 3);
println!("Success!")
println!("Success!");
}
```
@ -48,7 +48,7 @@ fn main() {
assert!(v == 3);
println!("Success!")
println!("Success!");
}
```
@ -59,7 +59,7 @@ fn main() {
let s = sum(1 , 2);
assert_eq!(s, 3);
println!("Success!")
println!("Success!");
}
fn sum(x: i32, y: i32) -> i32 {

2
en/src/collections/hashmap.md
View File

@ -9,7 +9,7 @@ The hash table implementation is a Rust port of Google’s [SwissTable](https://
### Basic Operations
1. 🌟🌟
```rust,editbale
```rust,editable
// FILL in the blanks and FIX the erros
use std::collections::HashMap;

42
en/src/compound-types/array.md
View File

@ -1,26 +1,26 @@
# Array
The type of array is `[T; Lengh]`, as you can see, array's lengh is part of their type signature. So their length must be known at compile time.
The type of array is `[T; Length]`, as you can see, array's length is part of their type signature. So their length must be known at compile time.
For example, you cant initialized an array as below:
For example, you cant initialize an array like below:
```rust
fn init_arr(n: i32) {
let arr = [1; n];
}
```
This will cause an error, because the compile have no idea of the exact size of the array in compile time.
This will cause an error, because the compiler has no idea of the exact size of the array at compile time.
1. 🌟
```rust,editable
fn main() {
// fill the blank with proper array type
// Fill the blank with proper array type
let arr: __ = [1, 2, 3, 4, 5];
// modify below to make it work
// Modify the code below to make it work
assert!(arr.len() == 4);
println!("Success!")
println!("Success!");
}
```
@ -28,16 +28,16 @@ fn main() {
```rust,editable
fn main() {
// we can ignore parts of the array type or even the whole type, let the compiler infer it for us
// We can ignore parts of the array type or even the whole type, let the compiler infer it for us
let arr0 = [1, 2, 3];
let arr: [_; 3] = ['a', 'b', 'c'];
// fill the blank
// Arrays are stack allocated, `std::mem::size_of_val` return the bytes which array occupies
// A char takes 4 byte in Rust: Unicode char
// Fill the blank
// Arrays are stack allocated, `std::mem::size_of_val` returns the bytes which an array occupies
// A char takes 4 bytes in Rust: Unicode char
assert!(std::mem::size_of_val(&arr) == __);
println!("Success!")
println!("Success!");
}
```
@ -46,13 +46,13 @@ fn main() {
```rust,editable
fn main() {
// fill the blank
// Fill the blank
let list: [i32; 100] = __ ;
assert!(list[0] == 1);
assert!(list.len() == 100);
println!("Success!")
println!("Success!");
}
```
@ -60,10 +60,10 @@ fn main() {
```rust,editable
fn main() {
// fix the error
// Fix the error
let _arr = [1, 2, '3'];
println!("Success!")
println!("Success!");
}
```
@ -73,28 +73,28 @@ fn main() {
fn main() {
let arr = ['a', 'b', 'c'];
let ele = arr[1]; // only modify this line to make the code work!
let ele = arr[1]; // Only modify this line to make the code work!
assert!(ele == 'a');
println!("Success!")
println!("Success!");
}
```
6. 🌟 Out of bounds indexing causes `panic`.
```rust,editable
// fix the error
// Fix the error
fn main() {
let names = [String::from("Sunfei"), "Sunface".to_string()];
// `get` returns an Option<T>, it's safe to use
// `Get` returns an Option<T>, it's safe to use
let name0 = names.get(0).unwrap();
// but indexing is not safe
// But indexing is not safe
let _name1 = &names[2];
println!("Success!")
println!("Success!");
}
```

38
en/src/compound-types/enum.md
View File

@ -3,7 +3,7 @@
```rust,editable
// fix the errors
// Fix the errors
enum Number {
Zero,
One,
@ -25,18 +25,18 @@ enum Number2 {
fn main() {
// a enum variant can be converted to a integer by `as`
// An enum variant can be converted to a integer by `as`
assert_eq!(Number::One, Number1::One);
assert_eq!(Number1::One, Number2::One);
println!("Success!")
println!("Success!");
}
```
2. 🌟 each enum variant can hold its own data.
2. 🌟 Each enum variant can hold its own data.
```rust,editable
// fill in the blank
// Fill in the blank
enum Message {
Quit,
Move { x: i32, y: i32 },
@ -45,17 +45,17 @@ enum Message {
}
fn main() {
let msg1 = Message::Move{__}; // instantiating with x = 1, y = 2
let msg2 = Message::Write(__); // instantiating with "hello, world!"
let msg1 = Message::Move{__}; // Instantiating with x = 1, y = 2
let msg2 = Message::Write(__); // Instantiating with "hello, world!"
println!("Success!")
println!("Success!");
}
```
3. 🌟🌟 we can get the data which a enum variant is holding by pattern match
3. 🌟🌟 We can get the data which an enum variant is holding by pattern match.
```rust,editable
// fill in the blank and fix the error
// Fill in the blank and fix the error
enum Message {
Quit,
Move { x: i32, y: i32 },
@ -72,7 +72,7 @@ fn main() {
panic!("NEVER LET THIS RUN！");
}
println!("Success!")
println!("Success!");
}
```
@ -80,7 +80,7 @@ fn main() {
```rust,editable
// fill in the blank and fix the errors
// Fill in the blank and fix the errors
enum Message {
Quit,
Move { x: i32, y: i32 },
@ -105,11 +105,11 @@ fn show_message(msg: Message) {
}
```
5. 🌟🌟 As there is no `null` in Rust, we have to use enum `Option<T>` to deal the cases when value is absent.
5. 🌟🌟 Since there is no `null` in Rust, we have to use enum `Option<T>` to deal with the cases when the value is absent.
```rust,editable
// fill in the blank to make the `println` work.
// also add some code to prevent the `panic` from running.
// 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);
@ -118,7 +118,7 @@ fn main() {
if let __ = six {
println!("{}", n);
println!("Success!")
println!("Success!");
}
panic!("NEVER LET THIS RUN！");
@ -133,7 +133,7 @@ fn plus_one(x: Option<i32>) -> Option<i32> {
```
6. 🌟🌟🌟🌟 implement a `linked-list` via enums.
6. 🌟🌟🌟🌟 Implement a `linked-list` via enums.
```rust,editable
@ -166,12 +166,12 @@ impl List {
// depends on the variant of `self`
// `self` has type `&List`, and `*self` has type `List`, matching on a
// concrete type `T` is preferred over a match on a reference `&T`
// after Rust 2018 you can use self here and tail (with no ref) below as well,
// After Rust 2018 you can use self here and tail (with no ref) below as well,
// rust will infer &s and ref tail.
// See https://doc.rust-lang.org/edition-guide/rust-2018/ownership-and-lifetimes/default-match-bindings.html
match *self {
// Can't take ownership of the tail, because `self` is borrowed;
// instead take a reference to the tail
// Instead take a reference to the tail
Cons(_, ref tail) => 1 + tail.len(),
// Base Case: An empty list has zero length
Nil => 0

32
en/src/compound-types/slice.md
View File

@ -4,18 +4,18 @@ Slices are similar to arrays, but their length is not known at compile time, so
1. 🌟🌟 Here, both `[i32]` and `str` are slice types, but directly using it will cause errors. You have to use the reference of the slice instead: `&[i32]`, `&str`.
```rust,editable
// fix the errors, DON'T add new lines!
// Fix the errors, DON'T add new lines!
fn main() {
let arr = [1, 2, 3];
let s1: [i32] = arr[0..2];
let s2: str = "hello, world" as str;
println!("Success!")
println!("Success!");
}
```
A slice reference is a two-word object, for simplicity reasons, from now on we will use slice instead of `slice reference`. The first word is a pointer to the data, and the second word is the length of the slice. The word size is the same as usize, determined by the processor architecture eg 64 bits on an x86-64. Slices can be used to borrow a section of an array, and have the type signature `&[T]`.
A slice reference is a two-word object, for simplicity reasons, from now on we will use slice instead of `slice reference`. The first word is a pointer to the data, and the second word is the length of the slice. The word size is the same as usize, determined by the processor architecture, eg 64 bits on an x86-64. Slices can be used to borrow a section of an array, and have the type signature `&[T]`.
2. 🌟🌟🌟
```rust,editable
@ -25,11 +25,11 @@ fn main() {
let slice = &arr[..2];
// modify '6' to make it work
// TIPS: slice( reference ) IS NOT an array, if it is an array, then `assert!` will passed: each of the two UTF-8 chars '中' and '国' occupies 3 bytes, 2 * 3 = 6
// Modify '6' to make it work
// TIPS: slice( reference ) IS NOT an array, if it is an array, then `assert!` will passed: Each of the two UTF-8 chars '中' and '国' occupies 3 bytes, 2 * 3 = 6
assert!(std::mem::size_of_val(&slice) == 6);
println!("Success!")
println!("Success!");
}
```
@ -38,15 +38,15 @@ fn main() {
fn main() {
let arr: [i32; 5] = [1, 2, 3, 4, 5];
// fill the blanks to make the code work
// Fill the blanks to make the code work
let slice: __ = __;
assert_eq!(slice, &[2, 3, 4]);
println!("Success!")
println!("Success!");
}
```
### string slices
### String slices
4. 🌟
```rust,editable
@ -54,12 +54,12 @@ fn main() {
let s = String::from("hello");
let slice1 = &s[0..2];
// fill the blank to make the code work, DON'T USE 0..2 again
// Fill the blank to make the code work, DON'T USE 0..2 again
let slice2 = &s[__];
assert_eq!(slice1, slice2);
println!("Success!")
println!("Success!");
}
```
@ -68,24 +68,24 @@ fn main() {
fn main() {
let s = "你好，世界";
// modify this line to make the code work
// Modify this line to make the code work
let slice = &s[0..2];
assert!(slice == "你");
println!("Success!")
println!("Success!");
}
```
6. 🌟🌟 `&String` can be implicitly converted into `&str`.
```rust,editable
// fix errors
// Fix errors
fn main() {
let mut s = String::from("hello world");
// here, &s is `&String` type, but `first_word` need a `&str` type.
// it works because `&String` can be implicitly converted to `&str, If you want know more ,this is called `Deref`
// Here, &s is `&String` type, but `first_word` need a `&str` type.
// It works because `&String` can be implicitly converted to `&str, If you want know more ,this is called `Deref`
let word = first_word(&s);
s.clear(); // error!

73
en/src/compound-types/string.md
View File

@ -1,17 +1,17 @@
# string
# String
The type of string literal `"hello, world"` is `&str`, e.g `let s: &str = "hello, world"`.
### str and &str
1. 🌟 We can't use `str` type in normal ways, but we can use `&str`
### Str and &str
1. 🌟 We can't use `str` type in normal ways, but we can use `&str`.
```rust,editable
// fix error without adding new line
// Fix error without adding new line
fn main() {
let s: str = "hello, world";
println!("Success!")
println!("Success!");
}
```
@ -20,9 +20,9 @@ fn main() {
```rust,editable
// fix the error with at least two solutions
// Fix the error with at least two solutions
fn main() {
let s: Box<str> = "hello, world".into();
let s: Box<str> = "hello, world".into();
greetings(s)
}
@ -37,7 +37,7 @@ fn greetings(s: &str) {
3. 🌟
```rust,editable
// fill the blank
// Fill the blank
fn main() {
let mut s = __;
s.push_str("hello, world");
@ -45,28 +45,28 @@ fn main() {
assert_eq!(s, "hello, world!");
println!("Success!")
println!("Success!");
}
```
4. 🌟🌟🌟
```rust,editable
// fix all errors without adding newline
// Fix all errors without adding newline
fn main() {
let s = String::from("hello");
let s = String::from("hello");
s.push(',');
s.push(" world");
s += "!".to_string();
println!("{}", s)
println!("{}", s);
}
```
5. 🌟🌟 `replace` can be used to replace substring
```rust,editable
// fill the blank
// Fill the blank
fn main() {
let s = String::from("I like dogs");
// Allocate new memory and store the modified string there
@ -74,17 +74,17 @@ fn main() {
assert_eq!(s1, "I like cats");
println!("Success!")
println!("Success!");
}
```
More `String` methods can be found under [String](https://doc.rust-lang.org/std/string/struct.String.html) module.
6. 🌟🌟 You can only concat a `String` with `&str`, and `String`'s ownership can be moved to another variable
6. 🌟🌟 You can only concat a `String` with `&str`, and `String`'s ownership can be moved to another variable.
```rust,editable
// fix errors without removing any line
// Fix errors without removing any line
fn main() {
let s1 = String::from("hello,");
let s2 = String::from("world!");
@ -100,9 +100,9 @@ Opsite to the seldom using of `str`, `&str` and `String` are used everywhere!
7. 🌟🌟 `&str` can be converted to `String` in two ways
```rust,editable
// fix error with at lest two solutions
// Fix error with at least two solutions
fn main() {
let s = "hello, world";
let s = "hello, world";
greetings(s)
}
@ -115,25 +115,25 @@ fn greetings(s: String) {
```rust,editable
// use two approaches to fix the error and without adding a new line
// Use two approaches to fix the error and without adding a new line
fn main() {
let s = "hello, world".to_string();
let s = "hello, world".to_string();
let s1: &str = s;
println!("Success!")
println!("Success!");
}
```
### string escapes
### String escapes
9. 🌟
```rust,editable
fn main() {
// You can use escapes to write bytes by their hexadecimal values
// fill the blank below to show "I'm writing Rust"
// Fill the blank below to show "I'm writing Rust"
let byte_escape = "I'm writing Ru\x73__!";
println!("What are you doing\x3F (\\x3F means ?) {}", byte_escape);
// ...or Unicode code points.
// ...Or Unicode code points.
let unicode_codepoint = "\u{211D}";
let character_name = "\"DOUBLE-STRUCK CAPITAL R\"";
@ -152,9 +152,9 @@ fn main() {
```rust,editable
/* Fill in the blank and fix the errors */
fn main() {
let raw_str = r"Escapes don't work here: \x3F \u{211D}";
// modify below line to make it work
assert_eq!(raw_str, "Escapes don't work here: ? ℝ");
// If you need quotes in a raw string, add a pair of #s
@ -166,15 +166,14 @@ fn main() {
let delimiter = r###"A string with "# in it. And even "##!"###;
println!("{}", delimiter);
// fill the blank
let long_delimiter = __;
assert_eq!(long_delimiter, "Hello, \"##\"");
println!("Success!")
println!("Success!");
}
```
### byte string
### Byte string
Want a string that's not UTF-8? (Remember, str and String must be valid UTF-8). Or maybe you want an array of bytes that's mostly text? Byte strings to the rescue!
**Example**:
@ -190,8 +189,8 @@ fn main() {
// Byte strings can have byte escapes...
let escaped = b"\x52\x75\x73\x74 as bytes";
// ...but no unicode escapes
// let escaped = b"\u{211D} is not allowed";
// ...But no unicode escapes
// let escaped = b"\u{211D} Is not allowed";
println!("Some escaped bytes: {:?}", escaped);
@ -208,7 +207,7 @@ fn main() {
like with normal raw strings"#;
// Byte strings don't have to be UTF-8
let shift_jis = b"\x82\xe6\x82\xa8\x82\xb1\x82\xbb"; // "ようこそ" in SHIFT-JIS
let shift_jis = b"\x82\xe6\x82\xa8\x82\xb1\x82\xbb"; // "ようこそ" In SHIFT-JIS
// But then they can't always be converted to `str`
match str::from_utf8(shift_jis) {
@ -220,29 +219,29 @@ fn main() {
A more detailed listing of the ways to write string literals and escape characters is given in the ['Tokens' chapter](https://doc.rust-lang.org/reference/tokens.html) of the Rust Reference.
### string index
### String index
11. 🌟🌟🌟 You can't use index to access a char in a string, but you can use slice `&s1[start..end]`.
```rust,editable
fn main() {
let s1 = String::from("hi,中国");
let h = s1[0]; //modify this line to fix the error, tips: `h` only takes 1 byte in UTF8 format
let h = s1[0]; // Modify this line to fix the error, tips: `h` only takes 1 byte in UTF8 format
assert_eq!(h, "h");
let h1 = &s1[3..5];//modify this line to fix the error, tips: `中` takes 3 bytes in UTF8 format
let h1 = &s1[3..5]; // Modify this line to fix the error, tips: `中` takes 3 bytes in UTF8 format
assert_eq!(h1, "中");
println!("Success!")
println!("Success!");
}
```
### operate on UTF8 string
### Operate on UTF8 string
12. 🌟
```rust,editable
fn main() {
// fill the blank to print each char in "你好，世界"
// Fill the blank to print each char in "你好，世界"
for c in "你好，世界".__ {
println!("{}", c)
}

54
en/src/compound-types/struct.md
View File

@ -1,10 +1,10 @@
# Struct
### There types of structs
### The types of structs
1. 🌟 We must specify concrete values for each of the fields in struct.
```rust,editable
// fix the error
// Fix the error
struct Person {
name: String,
age: u8,
@ -17,7 +17,7 @@ fn main() {
age,
};
println!("Success!")
println!("Success!");
}
```
@ -27,35 +27,35 @@ fn main() {
struct Unit;
trait SomeTrait {
// ...Some behavours defines here
// ...Some behaviors defined here.
}
// We don't care the the fields are in Unit, but we care its behaviors.
// We don't care about what fields are in the Unit, but we care about its behaviors.
// So we use a struct with no fields and implement some behaviors for it
impl SomeTrait for Unit { }
fn main() {
let u = Unit;
do_something_with_unit(u);
println!("Success!")
println!("Success!");
}
// fill the blank to make the code work
// Fill the blank to make the code work
fn do_something_with_unit(u: __) { }
```
3. 🌟🌟🌟 Tuple struct looks similar to tuples, it has added meaning the struct name provides but has no named fields. It's useful when you want give the whole tuple a name, but don't care the fields's names.
3. 🌟🌟🌟 Tuple struct looks similar to tuples, it has added meaning the struct name provides but has no named fields. It's useful when you want to give the whole tuple a name, but don't care about the fields's names.
```rust,editable
// fix the error and fill the blanks
// Fix the error and fill the blanks
struct Color(i32, i32, i32);
struct Point(i32, i32, i32);
fn main() {
let v = Point(__, __, __);
check_color(v);
println!("Success!")
println!("Success!");
}
fn check_color(p: Color) {
@ -66,13 +66,13 @@ fn check_color(p: Color) {
}
```
### Operate on structs
### Operating on structs
4. 🌟 You can make a whole struct mutable when instantiate it, but Rust doesn't allow us to mark only certain fields as mutable.
4. 🌟 You can make a whole struct mutable when instantiating it, but Rust doesn't allow us to mark only certain fields as mutable.
```rust,editable
// fill the blank and fix the error without adding/removing new line
// Fill the blank and fix the error without adding/removing new line
struct Person {
name: String,
age: u8,
@ -84,26 +84,26 @@ fn main() {
age,
};
// how can you believe sunface is only 18?
// How can you believe sunface is only 18?
p.age = 30;
// fill the lank
// Fill the blank
__ = String::from("sunfei");
println!("Success!")
println!("Success!");
}
```
5. 🌟 Using *field init shorthand syntax* to reduct repetitions.
5. 🌟 Using *field init shorthand syntax* to reduce repetitions.
```rust,editable
// fill the blank
// Fill the blank
struct Person {
name: String,
age: u8,
}
fn main() {
println!("Success!")
println!("Success!");
}
fn build_person(name: String, age: u8) -> Person {
@ -117,7 +117,7 @@ fn build_person(name: String, age: u8) -> Person {
6. 🌟 You can create instance from other instance with *struct update syntax*
```rust,editable
// fill the blank to make the code work
// Fill the blank to make the code work
struct User {
active: bool,
username: String,
@ -134,7 +134,7 @@ fn main() {
let u2 = set_email(u1);
println!("Success!")
println!("Success!");
}
fn set_email(u: User) -> User {
@ -146,11 +146,11 @@ fn set_email(u: User) -> User {
```
### Print the structs
7. 🌟🌟 We can use `#[derive(Debug)]` to [make a struct prinable](https://doc.rust-lang.org/book/ch05-02-example-structs.html?highlight=%23%5Bderive(Debug)%5D#adding-useful-functionality-with-derived-traits).
7. 🌟🌟 We can use `#[derive(Debug)]` to [make a struct printable](https://doc.rust-lang.org/book/ch05-02-example-structs.html?highlight=%23%5Bderive(Debug)%5D#adding-useful-functionality-with-derived-traits).
```rust,editable
// fill the blanks to make the code work
// Fill the blanks to make the code work
#[__]
struct Rectangle {
width: u32,
@ -160,13 +160,13 @@ struct Rectangle {
fn main() {
let scale = 2;
let rect1 = Rectangle {
width: dbg!(30 * scale), // print debug info to stderr and assign the value of `30 * scale` to `width`
width: dbg!(30 * scale), // Print debug info to stderr and assign the value of `30 * scale` to `width`
height: 50,
};
dbg!(&rect1); // print debug info to stderr
dbg!(&rect1); // Print debug info to stderr
println!(__, rect1); // print debug info to stdout
println!(__, rect1); // Print debug info to stdout
}
```
@ -209,7 +209,7 @@ fn main() {
8. 🌟🌟
```rust,editable
// fix errors to make it work
// Fix errors to make it work
#[derive(Debug)]
struct File {
name: String,

22
en/src/compound-types/tuple.md
View File

@ -6,29 +6,29 @@ fn main() {
let _t0: (u8,i16) = (0, -1);
// Tuples can be tuple's members
let _t1: (u8, (i16, u32)) = (0, (-1, 1));
// fill the blanks to make the code work
// Fill the blanks to make the code work
let t: (u8, __, i64, __, __) = (1u8, 2u16, 3i64, "hello", String::from(", world"));
println!("Success!")
println!("Success!");
}
```
2. 🌟 Members can be extracted from the tuple using indexing.
```rust,editable
// make it works
// Make it work
fn main() {
let t = ("i", "am", "sunface");
assert_eq!(t.1, "sunface");
println!("Success!")
println!("Success!");
}
```
3. 🌟 Long tuples cannot be printed
```rust,editable
// fix the error
// Fix the error
fn main() {
let too_long_tuple = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13);
println!("too long tuple: {:?}", too_long_tuple);
@ -41,14 +41,14 @@ fn main() {
fn main() {
let tup = (1, 6.4, "hello");
// fill the blank to make the code work
// Fill the blank to make the code work
let __ = tup;
assert_eq!(x, 1);
assert_eq!(y, "hello");
assert_eq!(z, 6.4);
println!("Success!")
println!("Success!");
}
```
@ -57,14 +57,14 @@ fn main() {
fn main() {
let (x, y, z);
// fill the blank
// Fill the blank
__ = (1, 2, 3);
assert_eq!(x, 3);
assert_eq!(y, 1);
assert_eq!(z, 2);
println!("Success!")
println!("Success!");
}
```
@ -72,13 +72,13 @@ fn main() {
```rust,editable
fn main() {
// fill the blank, need a few computations here.
// Fill the blank, need a few computations here.
let (x, y) = sum_multiply(__);
assert_eq!(x, 5);
assert_eq!(y, 6);
println!("Success!")
println!("Success!");
}
fn sum_multiply(nums: (i32, i32)) -> (i32, i32) {

5
en/src/elegant-code-base.md
View File

@ -30,10 +30,15 @@ Tutorial [`https://www.philippflenker.com/hecto/`](https://www.philippflenker.co
[This blog series](https://os.phil-opp.com) creates a small operating system in the Rust programming language. Each post is a small tutorial and includes all needed code, so you can follow along if you like. The source code is also available in the corresponding [Github repository](https://github.com/phil-opp/blog_os).
### 7. CodeCrafters.io: Build your own Git, Docker, SQLite, or Redis
On [CodeCrafters](https://codecrafters.io/for/rust), you can recreate your favorite developer tools from scratch. It's a hands-on, minimally-guided approach to master Rust, while appreciating the internals and documentation of popular technology that we use every day.
### 8. mini-redis
[mini-redis](https://github.com/tokio-rs/mini-redis) is an incomplete Redis client and server implementation using tokio, it has decent code base and detail explanations, very suitable for learning Rust and asynchronous programming.
---

60
en/src/flow-control.md
View File

@ -1,10 +1,10 @@
# Flow control
### if/else
### If/else
1. 🌟
```rust,editable
// fill in the blanks
// Fill in the blanks
fn main() {
let n = 5;
@ -18,10 +18,10 @@ fn main() {
}
```
2. 🌟🌟 `if/else` expression can be used in assignments.
2. 🌟🌟 `If/else` expression can be used in assignments.
```rust,editable
// fix the errors
// Fix the errors
fn main() {
let n = 5;
@ -40,7 +40,7 @@ fn main() {
}
```
### for
### For
3. 🌟 The `for in` construct can be used to iterate through an Iterator, e.g a range `a..b`.
```rust,editable
@ -52,7 +52,7 @@ fn main() {
}
}
println!("Success!")
println!("Success!");
}
```
@ -60,19 +60,19 @@ fn main() {
4. 🌟🌟
```rust,editable
// fix the errors without adding or removing lines
// Fix the errors without adding or removing lines
fn main() {
let names = [String::from("liming"),String::from("hanmeimei")];
for name in names {
// do something with name...
// Do something with name...
}
println!("{:?}", names);
let numbers = [1, 2, 3];
// the elements in numbers are Copy，so there is no move here
// The elements in numbers are Copy，so there is no move here
for n in numbers {
// do something with name...
// Do something with name...
}
println!("{:?}", numbers);
@ -84,19 +84,19 @@ fn main() {
fn main() {
let a = [4, 3, 2, 1];
// iterate the indexing and value in 'a'
// Iterate the indexing and value in 'a'
for (i,v) in a.__ {
println!("The {}th element is {}",i+1,v);
}
}
```
### while
### While
6. 🌟🌟 The `while` keyword can be used to run a loop when a condition is true.
```rust,editable
// fill in the blanks to make the last println! work !
// Fill in the blanks to make the last println! work !
fn main() {
// A counter variable
let mut n = 1;
@ -117,15 +117,15 @@ fn main() {
__;
}
println!("n reached {}, soloop is over",n);
println!("n reached {}, so loop is over",n);
}
```
### continue and break
7. 🌟 use `break` to break the loop.
### Continue and break
7. 🌟 Use `break` to break the loop.
```rust,editable
// fill in the blank
// Fill in the blank
fn main() {
let mut n = 0;
for i in 0..=100 {
@ -137,14 +137,14 @@ fn main() {
assert_eq!(n, 66);
println!("Success!")
println!("Success!");
}
```
8. 🌟🌟 `continue` will skip over the remaining code in current iteration and go to the next iteration.
```rust,editable
// fill in the blanks
// Fill in the blanks
fn main() {
let mut n = 0;
for i in 0..=100 {
@ -158,17 +158,17 @@ fn main() {
assert_eq!(n, 66);
println!("Success!")
println!("Success!");
}
```
### loop
### Loop
9. 🌟🌟 loop is usually used together with `break` or `continue`.
9. 🌟🌟 Loop is usually used together with `break` or `continue`.
```rust,editable
// fill in the blanks
// Fill in the blanks
fn main() {
let mut count = 0u32;
@ -196,14 +196,14 @@ fn main() {
assert_eq!(count, 5);
println!("Success!")
println!("Success!");
}
```
10. 🌟🌟 loop is an expression, so we can use it with `break` to return a value
10. 🌟🌟 Loop is an expression, so we can use it with `break` to return a value
```rust,editable
// fill in the blank
// Fill in the blank
fn main() {
let mut counter = 0;
@ -217,7 +217,7 @@ fn main() {
assert_eq!(result, 20);
println!("Success!")
println!("Success!");
}
```
@ -225,14 +225,14 @@ fn main() {
```rust,editable
// fill in the blank
// Fill in the blank
fn main() {
let mut count = 0;
'outer: loop {
'inner1: loop {
if count >= 20 {
// This would break only the inner1 loop
break 'inner1; // `break` is also ok
break 'inner1; // `break` is also works.
}
count += 2;
}
@ -252,7 +252,7 @@ fn main() {
assert!(count == __);
println!("Success!")
println!("Success!");
}
```

6
en/src/functional-programing/cloure.md
View File

@ -173,7 +173,7 @@ fn main() {
fn main() {
let mut s = String::new();
let update_string = |str| s.push_str(str);
let update_string = |str| s.push_str(str);
exec(update_string);
@ -260,7 +260,7 @@ move closures may still implement `Fn` or `FnMut`, even though they capture vari
fn main() {
let s = String::new();
let update_string = move || println!("{}",s);
let update_string = move || println!("{}",s);
exec(update_string);
}
@ -275,7 +275,7 @@ The following code also has no error:
fn main() {
let s = String::new();
let update_string = move || println!("{}",s);
let update_string = move || println!("{}",s);
exec(update_string);
}

14
en/src/generics-traits/advanced-traits.md
View File

@ -9,7 +9,7 @@ pub trait CacheableItem: Clone + Default + fmt::Debug + Decodable + Encodable {
}
```
Using of `Address` is much more clearable and convenient than `AsRef<[u8]> + Clone + fmt::Debug + Eq + Hash`.
Using of `Address` is much more clearer and convenient than `AsRef<[u8]> + Clone + fmt::Debug + Eq + Hash`.
1. 🌟🌟🌟
```rust,editable
@ -89,7 +89,7 @@ fn main() {
assert_eq!(Point { x: 2, y: 3 } - Point { x: 1, y: 0 },
Point { x: 1, y: 3 });
println!("Success!")
println!("Success!");
}
```
@ -110,7 +110,7 @@ trait AgeWidget {
fn get(&self) -> u8;
}
// A form with both a UsernameWidget and an AgeWidget
// A form with both a UsernameWidget and an AgeWidget.
struct Form {
username: String,
age: u8,
@ -141,10 +141,10 @@ fn main() {
let username = UsernameWidget::get(&form);
assert_eq!("rustacean".to_owned(), username);
let age = AgeWidget::get(&form); // you can also use `<Form as AgeWidget>::get`
let age = AgeWidget::get(&form); // You can also use `<Form as AgeWidget>::get`
assert_eq!(28, age);
println!("Success!")
println!("Success!");
}
```
@ -187,7 +187,7 @@ fn main() {
assert_eq!(__, "*waving arms furiously*");
println!("Success!")
println!("Success!");
}
```
@ -253,7 +253,7 @@ fn main() {
## Orphan Rules
We can’t implement external traits on external types. For example, we can’t implement the `Display` trait on `Vec<T>` within our own crate, because `Display` and `Vec<T>` are defined in the standard library and aren’t local to our crate.
This restriction is often called as the orphan rule, so named because the parent type is not present. This rule ensures that other people’s code can’t break your code and vice versa.
This restriction is often called the orphan rule, so named because the parent type is not present. This rule ensures that other people’s code can’t break your code and vice versa.
It’s possible to get around this restriction using the newtype pattern, which involves creating a new type in a tuple struct.

30
en/src/generics-traits/const-generics.md
View File

@ -25,15 +25,15 @@ impl<T: Debug, const N: usize> Debug for ArrayPair<T, N> {
fn foo<const N: usize>() {}
fn bar<T, const M: usize>() {
foo::<M>(); // ok: `M` is a const parameter
foo::<2021>(); // ok: `2021` is a literal
foo::<{20 * 100 + 20 * 10 + 1}>(); // ok: const expression contains no generic parameters
foo::<M>(); // Okay: `M` is a const parameter
foo::<2021>(); // Okay: `2021` is a literal
foo::<{20 * 100 + 20 * 10 + 1}>(); // Okay: const expression contains no generic parameters
foo::<{ M + 1 }>(); // error: const expression contains the generic parameter `M`
foo::<{ std::mem::size_of::<T>() }>(); // error: const expression contains the generic parameter `T`
foo::<{ M + 1 }>(); // Error: const expression contains the generic parameter `M`
foo::<{ std::mem::size_of::<T>() }>(); // Error: const expression contains the generic parameter `T`
let _: [u8; M]; // ok: `M` is a const parameter
let _: [u8; std::mem::size_of::<T>()]; // error: const expression contains the generic parameter `T`
let _: [u8; M]; // Okay: `M` is a const parameter
let _: [u8; std::mem::size_of::<T>()]; // Error: const expression contains the generic parameter `T`
}
fn main() {}
@ -89,14 +89,14 @@ fn main() {
}
];
println!("Success!")
println!("Success!");
}
```
2. 🌟🌟
```rust,editable
// fill in the blanks to make it work
// Fill in the blanks to make it work.
fn print_array<__>(__) {
println!("{:?}", arr);
}
@ -109,7 +109,7 @@ fn main() {
}
```
3. 🌟🌟🌟 Sometimes we want to limit the size of an variable, e.g when using in embedding evironments, then `const expressions` will fit your need.
3. 🌟🌟🌟 Sometimes we want to limit the size of a variable, e.g when using in embedding environments, then `const expressions` will fit your needs.
```rust,editable
#![allow(incomplete_features)]
@ -122,15 +122,15 @@ where
//...
}
// fix the errors in main
// Fix the errors in main.
fn main() {
check_size([0u8; 767]);
check_size([0i32; 191]);
check_size(["hello你好"; __]); // size of &str ?
check_size(["hello你好".to_string(); __]); // size of String?
check_size(['中'; __]); // size of char ?
check_size(["hello你好"; __]); // Size of &str ?
check_size([(); __].map(|_| "hello你好".to_string())); // Size of String?
check_size(['中'; __]); // Size of char ?
println!("Success!")
println!("Success!");
}

28
en/src/generics-traits/generics.md
View File

@ -4,7 +4,7 @@
1. 🌟🌟🌟
```rust,editable
// fill in the blanks to make it work
// Fill in the blanks to make it work
struct A; // Concrete type `A`.
struct S(A); // Concrete type `S`.
struct SGen<T>(T); // Generic type `SGen`.
@ -29,14 +29,14 @@ fn main() {
// Implicitly specified type parameter `char` to `generic()`.
generic(__);
println!("Success!")
println!("Success!");
}
```
2. 🌟🌟 A function call with explicitly specified type parameters looks like: `fun::<A, B, ...>()`.
```rust,editable
// implement the generic function below
// Implement the generic function below.
fn sum
fn main() {
@ -44,7 +44,7 @@ fn main() {
assert_eq!(50, sum(20, 30));
assert_eq!(2.46, sum(1.23, 1.23));
println!("Success!")
println!("Success!");
}
```
@ -54,38 +54,38 @@ fn main() {
3. 🌟
```rust,editable
// implement struct Point to make it work
// Implement struct Point to make it work.
fn main() {
let integer = Point { x: 5, y: 10 };
let float = Point { x: 1.0, y: 4.0 };
println!("Success!")
println!("Success!");
}
```
4. 🌟🌟
```rust,editable
// modify this struct to make the code work
// Modify this struct to make the code work
struct Point<T> {
x: T,
y: T,
}
fn main() {
// DON'T modify here
// DON'T modify this code.
let p = Point{x: 5, y : "hello".to_string()};
println!("Success!")
println!("Success!");
}
```
5. 🌟🌟
```rust,editable
// add generic for Val to make the code work, DON'T modify the code in `main`
// Add generic for Val to make the code work, DON'T modify the code in `main`.
struct Val {
val: f64,
}
@ -114,7 +114,7 @@ struct Point<T, U> {
}
impl<T, U> Point<T, U> {
// implement mixup to make it work, DON'T modify other code
// Implement mixup to make it work, DON'T modify other code.
fn mixup
}
@ -127,14 +127,14 @@ fn main() {
assert_eq!(p3.x, 5);
assert_eq!(p3.y, '中');
println!("Success!")
println!("Success!");
}
```
7. 🌟🌟
```rust,editable
// fix the errors to make the code work
// Fix the errors to make the code work.
struct Point<T> {
x: T,
y: T,
@ -148,7 +148,7 @@ impl Point<f32> {
fn main() {
let p = Point{x: 5, y: 10};
println!("{}",p.distance_from_origin())
println!("{}",p.distance_from_origin());
}
```

46
en/src/generics-traits/trait-object.md
View File

@ -4,7 +4,7 @@ In [traits chapter](https://practice.rs/generics-traits/traits.html#returning-ty
Also one limitation of arrays is that they can only store elements of one type, yeah, enum is a not bad solution when our items are a fixed set of types in compile time, but trait object are more flexible and powerful here.
## Returning Traits with dyn
The Rust compiler needs to know how much space a function's return type requires. Because the different implementations of a trait probably will need different amounts of memoery, this means function need to return a concrete type or the same type when using `impl Trait`, or it can return a trait object with `dyn`.
The Rust compiler needs to know how much space a function's return type requires. Because the different implementations of a trait probably will need different amounts of memory, this means function need to return a concrete type or the same type when using `impl Trait`, or it can return a trait object with `dyn`.
1. 🌟🌟🌟
```rust,editable
@ -39,26 +39,26 @@ impl Bird for Swan {
}
fn main() {
// FILL in the blank
// FILL in the blank.
let duck = __;
duck.swim();
let bird = hatch_a_bird(2);
// this bird has forgotten how to swim, so below line will cause an error
// This bird has forgotten how to swim, so below line will cause an error.
// bird.swim();
// but it can quak
// But it can quak.
assert_eq!(bird.quack(), "duck duck");
let bird = hatch_a_bird(1);
// this bird has forgotten how to fly, so below line will cause an error
// This bird has forgotten how to fly, so below line will cause an error.
// bird.fly();
// but it can quak too
// But it can quak too.
assert_eq!(bird.quack(), "swan swan");
println!("Success!")
println!("Success!");
}
// IMPLEMENT this function
// IMPLEMENT this function.
fn hatch_a_bird...
```
@ -95,13 +95,13 @@ impl Bird for Swan {
}
fn main() {
// FILL in the blank to make the code work
// FILL in the blank to make the code work.
let birds __;
for bird in birds {
bird.quack();
// when duck and swan turns into Bird, they all forgot how to fly, only remeber how to quack
// so, the below code will cause an error
// When duck and swan turn into Birds, they all forgot how to fly, only remember how to quack.
// So, the code below will cause an error.
// bird.fly();
}
}
@ -113,7 +113,7 @@ fn main() {
3. 🌟🌟
```rust,editable
// FILL in the blanks
// FILL in the blanks.
trait Draw {
fn draw(&self) -> String;
}
@ -134,13 +134,13 @@ fn main() {
let x = 1.1f64;
let y = 8u8;
// draw x
// Draw x.
draw_with_box(__);
// draw y
// Draw y.
draw_with_ref(&y);
println!("Success!")
println!("Success!");
}
fn draw_with_box(x: Box<dyn Draw>) {
@ -153,11 +153,11 @@ fn draw_with_ref(x: __) {
```
## Static and Dynamic dispatch
when we use trait bounds on generics: the compiler generates nongeneric implementations of functions and methods for each concrete type that we use in place of a generic type parameter. The code that results from monomorphization is doing static dispatch, which is when the compiler knows what method you’re calling at compile time.
When we use trait bounds on generics, the compiler generates nongeneric implementations of functions and methods for each concrete type that we use in place of a generic type parameter. The code that results from monomorphization is doing static dispatch, which is when the compiler knows what method you’re calling at compile time.
When we use trait objects, Rust must use dynamic dispatch. The compiler doesn’t know all the types that might be used with the code that is using trait objects, so it doesn’t know which method implemented on which type to call. Instead, at runtime, Rust uses the pointers inside the trait object to know which method to call. There is a runtime cost when this lookup happens that doesn’t occur with static dispatch. Dynamic dispatch also prevents the compiler from choosing to inline a method’s code, which in turn prevents some optimizations.
However, we did get extra flexibility when using dynamic dispatch.
However, we do get extra flexibility when using dynamic dispatch.
4. 🌟🌟
```rust,editable
@ -174,10 +174,10 @@ impl Foo for String {
fn method(&self) -> String { format!("string: {}", *self) }
}
// IMPLEMENT below with generics
// IMPLEMENT below with generics.
fn static_dispatch...
// implement below with trait objects
// Implement below with trait objects.
fn dynamic_dispatch...
fn main() {
@ -187,7 +187,7 @@ fn main() {
static_dispatch(x);
dynamic_dispatch(&y);
println!("Success!")
println!("Success!");
}
```
@ -200,8 +200,8 @@ You can only make object-safe traits into trait objects. A trait is object safe
5. 🌟🌟🌟🌟
```rust,editable
// Use at least two approaches to make it work
// DON'T add/remove any code line
// Use at least two approaches to make it work.
// DON'T add/remove any code line.
trait MyTrait {
fn f(&self) -> Self;
}
@ -222,7 +222,7 @@ fn main() {
my_function(Box::new(13_u32));
my_function(Box::new(String::from("abc")));
println!("Success!")
println!("Success!");
}
```

48
en/src/generics-traits/traits.md
View File

@ -81,8 +81,8 @@ fn main() {
1. 🌟🌟
```rust,editable
// fill in the two impl blocks to make the code work
// DON'T modify the code in `main`
// Fill in the two impl blocks to make the code work.
// DON'T modify the code in `main`.
trait Hello {
fn say_hi(&self) -> String {
String::from("hi")
@ -107,7 +107,7 @@ fn main() {
assert_eq!(t.say_hi(), "Hi, I'm your new teacher");
assert_eq!(t.say_something(), "I'm not a bad teacher");
println!("Success!")
println!("Success!");
}
```
@ -135,7 +135,7 @@ impl Inches {
}
// ADD some attributes to make the code work!
// DON'T modify other codes!
// DON'T modify other code!
struct Seconds(i32);
fn main() {
@ -171,23 +171,23 @@ In Rust, many of the operators can be overloaded via traits. That is, some opera
use std::ops;
// implement fn multiply to make the code work
// As mentiond above, `+` needs `T` to implement `std::ops::Add` Trait
// so, what about `*` ? You can find the answer here: https://doc.rust-lang.org/core/ops/
// Implement fn multiply to make the code work.
// As mentiond above, `+` needs `T` to implement `std::ops::Add` Trait.
// So, what about `*`? You can find the answer here: https://doc.rust-lang.org/core/ops/
fn multipl
fn main() {
assert_eq!(6, multiply(2u8, 3u8));
assert_eq!(5.0, multiply(1.0, 5.0));
println!("Success!")
println!("Success!");
}
```
4. 🌟🌟🌟
```rust,editable
// fix the errors, DON'T modify the code in `main`
// Fix the errors, DON'T modify the code in `main`.
use std::ops;
struct Foo;
@ -217,12 +217,12 @@ impl ops::Sub<Foo> for Bar {
}
fn main() {
// DON'T modify the below code
// you need to derive some trait for FooBar to make it comparable
// DON'T modify the code below.
// You need to derive some trait for FooBar to make it comparable.
assert_eq!(Foo + Bar, FooBar);
assert_eq!(Foo - Bar, BarFoo);
println!("Success!")
println!("Success!");
}
```
@ -232,8 +232,8 @@ Instead of a concrete type for the item parameter, we specify the impl keyword a
5. 🌟🌟🌟
```rust,editable
// implement `fn summary` to make the code work
// fix the errors without removing any code line
// Implement `fn summary` to make the code work.
// Fix the errors without removing any code line
trait Summary {
fn summarize(&self) -> String;
}
@ -281,14 +281,14 @@ fn main() {
println!("{:?}", weibo);
}
// implement `fn summary` below
// Implement `fn summary` below.
```
### Returning Types that Implement Traits
We can also use the impl Trait syntax in the return position to return a value of some type that implements a trait.
However, you can only use impl Trait if you’re returning a single type, using Trait Objects instead when you really need to return serveral types.
However, you can only use impl Trait if you’re returning a single type, use Trait Objects instead when you really need to return several types.
6. 🌟🌟
```rust,editable
@ -313,7 +313,7 @@ impl Animal for Cow {
}
// Returns some struct that implements Animal, but we don't know which one at compile time.
// FIX the erros here, you can make a fake random, or you can use trait object
// FIX the errors here, you can make a fake random, or you can use trait object.
fn random_animal(random_number: f64) -> impl Animal {
if random_number < 0.5 {
Sheep {}
@ -340,7 +340,7 @@ fn main() {
assert_eq!(sum(1, 2), 3);
}
// implement `fn sum` with trait bound in two ways
// Implement `fn sum` with trait bound in two ways.
fn sum<T>(x: T, y: T) -> T {
x + y
}
@ -348,7 +348,7 @@ fn sum<T>(x: T, y: T) -> T {
8. 🌟🌟
```rust,editable
// FIX the errors
// FIX the errors.
struct Pair<T> {
x: T,
y: T,
@ -388,10 +388,10 @@ fn main() {
9. 🌟🌟🌟
```rust,editable
// fill in the blanks to make it work
// Fill in the blanks to make it work
fn example1() {
// `T: Trait` is the commonly used way
// `T: Fn(u32) -> u32` specifies that we can only pass a closure to `T`
// `T: Trait` is the commonly used way.
// `T: Fn(u32) -> u32` specifies that we can only pass a closure to `T`.
struct Cacher<T: Fn(u32) -> u32> {
calculation: T,
value: Option<u32>,
@ -424,7 +424,7 @@ fn example1() {
fn example2() {
// We can also use `where` to constrain `T`
// We can also use `where` to construct `T`
struct Cacher<T>
where T: Fn(u32) -> u32,
{
@ -465,7 +465,7 @@ fn main() {
example1();
example2();
println!("Success!")
println!("Success!");
}
```

52
en/src/method.md
View File

@ -1,4 +1,4 @@
# Associated function & Method
# Associated functions & Methods
## Examples
```rust,editable
@ -7,7 +7,7 @@ struct Point {
y: f64,
}
// Implementation block, all `Point` associated functions & methods go in here
// Implementation block, all `Point` associated functions & methods go in here.
impl Point {
// This is an "associated function" because this function is associated with
// a particular type, that is, Point.
@ -30,11 +30,11 @@ struct Rectangle {
}
impl Rectangle {
// This is a method
// This is a method.
// `&self` is sugar for `self: &Self`, where `Self` is the type of the
// caller object. In this case `Self` = `Rectangle`
fn area(&self) -> f64 {
// `self` gives access to the struct fields via the dot operator
// `self` gives access to the struct fields via the dot operator.
let Point { x: x1, y: y1 } = self.p1;
let Point { x: x2, y: y2 } = self.p2;
@ -61,7 +61,7 @@ impl Rectangle {
}
}
// `Pair` owns resources: two heap allocated integers
// `Pair` owns resources: two heap allocated integers.
struct Pair(Box<i32>, Box<i32>);
impl Pair {
@ -73,7 +73,7 @@ impl Pair {
println!("Destroying Pair({}, {})", first, second);
// `first` and `second` go out of scope and get freed
// `first` and `second` go out of scope and get freed.
}
}
@ -84,7 +84,7 @@ fn main() {
p2: Point::new(3.0, 4.0),
};
// Methods are called using the dot operator
// Methods are called using the dot operator.
// Note that the first argument `&self` is implicitly passed, i.e.
// `rectangle.perimeter()` === `Rectangle::perimeter(&rectangle)`
println!("Rectangle perimeter: {}", rectangle.perimeter());
@ -96,7 +96,7 @@ fn main() {
};
// Error! `rectangle` is immutable, but this method requires a mutable
// object
// object.
//rectangle.translate(1.0, 0.0);
// TODO ^ Try uncommenting this line
@ -116,7 +116,7 @@ fn main() {
## Exercises
### Method
1. 🌟🌟 Methods are similar to functions: declare with `fn`, have parameters and a return value. Unlike functions, methods are defined within the context of a struct (or an enum or a trait object), and their first parameter is always `self`, which represents the instance of the struct the method is being called on.
1. 🌟🌟 Methods are similar to functions: Declare with `fn`, have parameters and a return value. Unlike functions, methods are defined within the context of a struct (or an enum or a trait object), and their first parameter is always `self`, which represents the instance of the struct the method is being called on.
```rust,editable
struct Rectangle {
width: u32,
@ -124,7 +124,7 @@ struct Rectangle {
}
impl Rectangle {
// complete the area method which return the area of a Rectangle
// Complete the area method which return the area of a Rectangle.
fn area
}
@ -133,11 +133,11 @@ fn main() {
assert_eq!(rect1.area(), 1500);
println!("Success!")
println!("Success!");
}
```
2. 🌟🌟 `self` will take the ownership of current struct instance, however, `&self` will only borrow a reference from the instance
2. 🌟🌟 `self` will take the ownership of current struct instance, however, `&self` will only borrow a reference from the instance.
```rust,editable
// Only fill in the blanks, DON'T remove any line!
@ -155,9 +155,9 @@ fn main() {
let light = TrafficLight{
color: "red".to_owned(),
};
// Don't take the ownership of `light` here
// Don't take the ownership of `light` here.
light.show_state();
// ..otherwise, there will be an error below
// ... Otherwise, there will be an error below
println!("{:?}", light);
}
```
@ -168,23 +168,23 @@ struct TrafficLight {
}
impl TrafficLight {
// using `Self` to fill in the blank
// Using `Self` to fill in the blank.
pub fn show_state(__) {
println!("the current state is {}", self.color);
}
// fill in the blank, DON'T use any variants of `Self`
pub fn change_state() {
// Fill in the blank, DON'T use any variants of `Self`.
pub fn change_state(__) {
self.color = "green".to_string()
}
}
fn main() {
println!("Success!")
println!("Success!");
}
```
### Associated function
### Associated functions
4. 🌟🌟 All functions defined within an `impl` block are called associated functions because they’re associated with the type named after the `impl`. We can define associated functions that don’t have `self` as their first parameter (and thus are not methods) because they don’t need an instance of the type to work with.
@ -195,9 +195,9 @@ struct TrafficLight {
}
impl TrafficLight {
// 1. implement a assotiated function `new`,
// 2. it will return a TrafficLight contains color "red"
// 3. must use `Self`, DONT use `TrafficLight` in fn signatures or body
// 1. Implement an assotiated function `new`,
// 2. It will return a TrafficLight contains color "red"
// 3. Must use `Self`, DONT use `TrafficLight` in fn signatures or body
pub fn new()
pub fn get_state(&self) -> &str {
@ -209,7 +209,7 @@ fn main() {
let light = TrafficLight::new();
assert_eq!(light.get_state(), "red");
println!("Success!")
println!("Success!");
}
```
@ -222,7 +222,7 @@ struct Rectangle {
height: u32,
}
// using multiple `impl` blocks to rewrite the code below
// Using multiple `impl` blocks to rewrite the code below.
impl Rectangle {
fn area(&self) -> u32 {
self.width * self.height
@ -235,7 +235,7 @@ impl Rectangle {
fn main() {
println!("Success!")
println!("Success!");
}
```
@ -251,7 +251,7 @@ enum TrafficLightColor {
Green,
}
// implement TrafficLightColor with a method
// Implement TrafficLightColor with a method.
impl TrafficLightColor {
}

54
en/src/ownership/borrowing.md
View File

@ -6,10 +6,10 @@
fn main() {
let x = 5;
// fill the blank
// Fill the blank
let p = __;
println!("the memory address of x is {:p}", p); // one possible output: 0x16fa3ac84
println!("the memory address of x is {:p}", p); // One possible output: 0x16fa3ac84
}
```
@ -20,23 +20,23 @@ fn main() {
let x = 5;
let y = &x;
// modify this line only
// Modify this line only
assert_eq!(5, y);
println!("Success!")
println!("Success!");
}
```
3. 🌟
```rust,editable
// fix error
// Fix error
fn main() {
let mut s = String::from("hello, ");
borrow_object(s);
println!("Success!")
println!("Success!");
}
fn borrow_object(s: &String) {}
@ -45,13 +45,13 @@ fn borrow_object(s: &String) {}
4. 🌟
```rust,editable
// fix error
// Fix error
fn main() {
let mut s = String::from("hello, ");
push_str(s);
println!("Success!")
println!("Success!");
}
fn push_str(s: &mut String) {
@ -65,16 +65,16 @@ fn push_str(s: &mut String) {
fn main() {
let mut s = String::from("hello, ");
// fill the blank to make it work
// Fill the blank to make it work
let p = __;
p.push_str("world");
println!("Success!")
println!("Success!");
}
```
#### ref
#### Ref
`ref` can be used to take references to a value, similar to `&`.
6. 🌟🌟🌟
@ -84,18 +84,18 @@ fn main() {
let c = '中';
let r1 = &c;
// fill the blank，dont change other code
// Fill the blank，dont change other code
let __ r2 = c;
assert_eq!(*r1, *r2);
// check the equality of the two address strings
// Check the equality of the two address strings
assert_eq!(get_addr(r1),get_addr(r2));
println!("Success!")
println!("Success!");
}
// get memory address string
// Get memory address string
fn get_addr(r: &char) -> String {
format!("{:p}", r)
}
@ -105,8 +105,8 @@ fn get_addr(r: &char) -> String {
7. 🌟
```rust,editable
// remove something to make it work
// don't remove a whole line !
// Remove something to make it work
// Don't remove a whole line !
fn main() {
let mut s = String::from("hello");
@ -115,21 +115,21 @@ fn main() {
println!("{}, {}", r1, r2);
println!("Success!")
println!("Success!");
}
```
#### Mutablity
8. 🌟 Error: Borrow a immutable object as mutable
#### Mutability
8. 🌟 Error: Borrow an immutable object as mutable
```rust,editable
fn main() {
//fix error by modifying this line
// Fix error by modifying this line
let s = String::from("hello, ");
borrow_object(&mut s);
println!("Success!")
println!("Success!");
}
fn borrow_object(s: &mut String) {}
@ -138,7 +138,7 @@ fn borrow_object(s: &mut String) {}
9. 🌟🌟 Ok: Borrow a mutable object as immutable
```rust,editable
// this code has no errors!
// This code has no errors!
fn main() {
let mut s = String::from("hello, ");
@ -146,7 +146,7 @@ fn main() {
s.push_str("world");
println!("Success!")
println!("Success!");
}
fn borrow_object(s: &String) {}
@ -156,7 +156,7 @@ fn borrow_object(s: &String) {}
10. 🌟🌟
```rust,editable
// comment one line to make it work
// Comment one line to make it work
fn main() {
let mut s = String::from("hello, ");
@ -178,8 +178,8 @@ fn main() {
let r1 = &mut s;
let r2 = &mut s;
// add one line below to make a compiler error: cannot borrow `s` as mutable more than once at a time
// you can't use r1 and r2 at the same time
// Add one line below to make a compiler error: cannot borrow `s` as mutable more than once at a time
// You can't use r1 and r2 at the same time
}
```

20
en/src/ownership/ownership.md
View File

@ -4,7 +4,7 @@
```rust,editable
fn main() {
// use as many approaches as you can to make it work
// Use as many approaches as you can to make it work
let x = String::from("hello, world");
let y = x;
println!("{},{}",x,y);
@ -39,7 +39,7 @@ fn main() {
// Only modify the code below!
fn give_ownership() -> String {
let s = String::from("hello, world");
// convert String to Vec
// Convert String to Vec
let _s = s.into_bytes();
s
}
@ -47,7 +47,7 @@ fn give_ownership() -> String {
4. 🌟🌟
```rust,editable
// fix the error without removing code line
// Fix the error without removing code line
fn main() {
let s = String::from("hello, world");
@ -63,7 +63,7 @@ fn print_str(s: String) {
5. 🌟🌟
```rust, editable
// don't use clone ,use copy instead
// Don't use clone ,use copy instead
fn main() {
let x = (1, 2, (), "hello".to_string());
let y = x.clone();
@ -80,12 +80,12 @@ Mutability can be changed when ownership is transferred.
fn main() {
let s = String::from("hello, ");
// modify this line only !
// Modify this line only !
let s1 = s;
s1.push_str("world");
println!("Success!")
println!("Success!");
}
```
@ -95,13 +95,13 @@ fn main() {
fn main() {
let x = Box::new(5);
let ... // implement this line, dont change other lines!
let ... // Implement this line, dont change other lines!
*y = 4;
assert_eq!(*x, 5);
println!("Success!")
println!("Success!");
}
```
@ -148,7 +148,7 @@ fn main() {
let _s = t.0;
// modify this line only, don't use `_s`
// Modify this line only, don't use `_s`
println!("{:?}", t);
}
```
@ -159,7 +159,7 @@ fn main() {
fn main() {
let t = (String::from("hello"), String::from("world"));
// fill the blanks
// Fill the blanks
let (__, __) = __;
println!("{:?}, {:?}, {:?}", s1, s2, t); // -> "hello", "world", ("hello", "world")

52
en/src/pattern-match/match-iflet.md
View File

@ -1,10 +1,10 @@
# match, if let
# Match, if let
### match
### Match
1. 🌟🌟
```rust,editable
// fill the blanks
// Fill the blanks
enum Direction {
East,
West,
@ -16,7 +16,7 @@ fn main() {
let dire = Direction::South;
match dire {
Direction::East => println!("East"),
__ => { // matching South or North here
__ => { // Matching South or North here
println!("South or North");
},
_ => println!(__),
@ -24,13 +24,13 @@ fn main() {
}
```
2. 🌟🌟 match is an expression, so we can use it in assignments
2. 🌟🌟 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:
// Fill the blank with a match expression:
//
// boolean = true => binary = 1
// boolean = false => binary = 0
@ -38,14 +38,14 @@ fn main() {
assert_eq!(binary, 1);
println!("Success!")
println!("Success!");
}
```
3. 🌟🌟 using match to get the data an enum variant holds
3. 🌟🌟 Using match to get the data an enum variant holds.
```rust,editable
// fill in the blanks
// Fill in the blanks
enum Message {
Quit,
Move { x: i32, y: i32 },
@ -64,7 +64,7 @@ fn main() {
show_message(msg)
}
println!("Success!")
println!("Success!");
}
fn show_message(msg: Message) {
@ -83,7 +83,7 @@ fn show_message(msg: Message) {
```
### matches!
[`matches!`](https://doc.rust-lang.org/stable/core/macro.matches.html) looks like `match`, but can do something different
[`matches!`](https://doc.rust-lang.org/stable/core/macro.matches.html) looks like `match`, but can do something different.
4. 🌟🌟
```rust,editable
@ -91,12 +91,12 @@ fn show_message(msg: Message) {
fn main() {
let alphabets = ['a', 'E', 'Z', '0', 'x', '9' , 'Y'];
// fill the blank with `matches!` to make the code work
// Fill the blank with `matches!` to make the code work
for ab in alphabets {
assert!(__)
}
println!("Success!")
println!("Success!");
}
```
@ -113,19 +113,19 @@ fn main() {
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
if e == MyEnum::Foo { // Fix the error by changing only this line
count += 1;
}
}
assert_eq!(count, 2);
println!("Success!")
println!("Success!");
}
```
### if let
For some cases, when matching enums, `match` is too heavy, we can use `if let` instead.
### If let
For some cases, when matching enums, `match` is too heavy. We can use `if let` instead.
6. 🌟
```rust,editable
@ -133,12 +133,12 @@ For some cases, when matching enums, `match` is too heavy, we can use `if let` i
fn main() {
let o = Some(7);
// remove the whole `match` block, using `if let` instead
// Remove the whole `match` block, using `if let` instead
match o {
Some(i) => {
println!("This is a really long string and `{:?}`", i);
println!("Success!")
println!("Success!");
}
_ => {}
};
@ -148,7 +148,7 @@ fn main() {
7. 🌟🌟
```rust,editable
// fill in the blank
// Fill in the blank
enum Foo {
Bar(u8)
}
@ -159,7 +159,7 @@ fn main() {
__ {
println!("foobar holds the value: {}", i);
println!("Success!")
println!("Success!");
}
}
```
@ -176,7 +176,7 @@ enum Foo {
fn main() {
let a = Foo::Qux(10);
// remove the codes below, using `match` instead
// Remove the codes below, using `match` instead
if let Foo::Bar = a {
println!("match foo::bar")
} else if let Foo::Baz = a {
@ -191,15 +191,15 @@ fn main() {
9. 🌟🌟
```rust,editable
// fix the errors in-place
// Fix the errors in-place
fn main() {
let age = Some(30);
if let Some(age) = age { // create a new variable with the same name as previous `age`
if let Some(age) = age { // Create a new variable with the same name as previous `age`
assert_eq!(age, Some(30));
} // the new variable `age` goes out of scope here
} // The new variable `age` goes out of scope here
match age {
// match can also introduce a new shadowed variable
// Match can also introduce a new shadowed variable
Some(age) => println!("age is a new variable, it's value is {}",age),
_ => ()
}

26
en/src/pattern-match/patterns.md
View File

@ -1,16 +1,16 @@
# Patterns
1. 🌟🌟 use `|` to match several values, use `..=` to match a inclusive range
1. 🌟🌟 Use `|` to match several values, use `..=` to match an inclusive range.
```rust,editable
fn main() {}
fn match_number(n: i32) {
match n {
// match a single value
// Match a single value
1 => println!("One!"),
// fill in the blank with `|`, DON'T use `..` ofr `..=`
// Fill in the blank with `|`, DON'T use `..` or `..=`
__ => println!("match 2 -> 5"),
// match an inclusive range
// Match an inclusive range
6..=10 => {
println!("match 6 -> 10")
},
@ -21,7 +21,7 @@ fn match_number(n: i32) {
}
```
2. 🌟🌟🌟 The `@` operator lets us create a variable that holds a value at the same time we are testing that value to see whether it matches a pattern.
2. 🌟🌟🌟 The `@` operator lets us create a variable that holds a value, at the same time we are testing that value to see whether it matches a pattern.
```rust,editable
struct Point {
@ -30,12 +30,12 @@ struct Point {
}
fn main() {
// fill in the blank to let p match the second arm
// Fill in the blank to let p match the second arm
let p = Point { x: __, y: __ };
match p {
Point { x, y: 0 } => println!("On the x axis at {}", x),
// second arm
// Second arm
Point { x: 0..=5, y: y@ (10 | 20 | 30) } => println!("On the y axis at {}", y),
Point { x, y } => println!("On neither axis: ({}, {})", x, y),
}
@ -46,7 +46,7 @@ fn main() {
```rust,editable
// fix the errors
// Fix the errors
enum Message {
Hello { id: i32 },
}
@ -69,7 +69,7 @@ fn main() {
4. 🌟🌟 A match guard is an additional if condition specified after the pattern in a match arm that must also match, along with the pattern matching, for that arm to be chosen.
```rust,editable
// fill in the blank to make the code work, `split` MUST be used
// Fill in the blank to make the code work, `split` MUST be used
fn main() {
let num = Some(4);
let split = 5;
@ -79,14 +79,14 @@ fn main() {
None => (),
}
println!("Success!")
println!("Success!");
}
```
5. 🌟🌟 Ignoring remaining parts of the value with `..`
```rust,editable
// fill the blank to make the code work
// Fill the blank to make the code work
fn main() {
let numbers = (2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048);
@ -97,11 +97,11 @@ fn main() {
}
}
println!("Success!")
println!("Success!");
}
```
6. 🌟🌟 Using pattern `&mut V` to match a mutable reference needs you to be very careful due to `V` being a value after matching
6. 🌟🌟 Using pattern `&mut V` to match a mutable reference needs you to be very careful, due to `V` being a value after matching.
```rust,editable
// FIX the error with least changing

52
en/src/variables.md
View File

@ -1,29 +1,29 @@
# Variables
### Binding and mutablity
### Binding and mutability
1. 🌟 A variable can be used only if it has been initialized.
```rust,editable
// fix the error below with least modifying
// Fix the error below with least amount of modification to the code
fn main() {
let x: i32; // uninitialized but using, ERROR !
let y: i32; // uninitialized but also unusing, only warning
let x: i32; // Uninitialized but used, ERROR !
let y: i32; // Uninitialized but also unused, only a Warning !
assert_eq!(x, 5);
println!("Success!")
println!("Success!");
}
```
2. 🌟 Use `mut` to mark a variable as mutable.
```rust,editable
// fill the blanks in code to make it compile
// Fill the blanks in the code to make it compile
fn main() {
let __ = 1;
let __ = 1;
__ += 2;
assert_eq!(x, 3);
println!("Success!")
println!("Success!");
}
```
@ -33,7 +33,7 @@ A scope is the range within the program for which the item is valid.
3. 🌟
```rust,editable
// fix the error below with least modifying
// Fix the error below with least amount of modification
fn main() {
let x: i32 = 10;
{
@ -47,7 +47,7 @@ fn main() {
4. 🌟🌟
```rust,editable
// fix the error with using of define_x
// Fix the error with the use of define_x
fn main() {
println!("{}, world", x);
}
@ -63,7 +63,7 @@ You can declare a new variable with the same name as a previous variable, here w
5. 🌟🌟
```rust,editable
// only modify `assert_eq!` to make the `println!` work(print `42` in terminal)
// Only modify `assert_eq!` to make the `println!` work(print `42` in terminal)
fn main() {
let x: i32 = 5;
{
@ -73,7 +73,7 @@ fn main() {
assert_eq!(x, 12);
let x = 42;
let x = 42;
println!("{}", x); // Prints "42".
}
```
@ -81,28 +81,28 @@ fn main() {
6. 🌟🌟
```rust,editable
// remove a line in code to make it compile
// Remove a line in the code to make it compile
fn main() {
let mut x: i32 = 1;
x = 7;
// shadowing and re-binding
// Shadowing and re-binding
let x = x;
x += 3;
let y = 4;
// shadowing
// Shadowing
let y = "I can also be bound to text!";
println!("Success!")
println!("Success!");
}
```
### Unused varibles
1. fix the warning below with :
### Unused variables
1. Fix the warning below with :
- 🌟 only one solution
- 🌟🌟 two distinct solutions
- 🌟 Only one solution
- 🌟🌟 Two distinct solutions
> Note: none of the solutions is to remove the line `let x = 1`
@ -112,7 +112,7 @@ fn main() {
let x = 1;
}
// warning: unused variable: `x`
// Warning: unused variable: `x`
```
### Destructuring
@ -122,7 +122,7 @@ fn main() {
```rust,editable
// fix the error below with least modifying
// Fix the error below with least amount of modification
fn main() {
let (x, y) = (1, 2);
x += 2;
@ -130,12 +130,12 @@ fn main() {
assert_eq!(x, 3);
assert_eq!(y, 2);
println!("Success!")
println!("Success!");
}
```
### Destructuring assignments
Introducing in Rust 1.59: You can now use tuple, slice, and struct patterns as the left-hand side of an assignment.
Introduced in Rust 1.59: You can now use tuple, slice, and struct patterns as the left-hand side of an assignment.
9. 🌟🌟
@ -147,10 +147,10 @@ fn main() {
let (x, y);
(x,..) = (3, 4);
[.., y] = [1, 2];
// fill the blank to make the code work
// Fill the blank to make the code work
assert_eq!([x,y], __);
println!("Success!")
println!("Success!");
}
```

2
en/src/why-exercise.md
View File

@ -1,5 +1,5 @@
<div align="center">
<img height="150" src="https://github.com/sunface/rust-by-practice/blob/master/en/assets/logo.png?raw=true">
<img src="https://github.com/sunface/rust-by-practice/blob/master/en/assets/header.png?raw=true">
</div>
<p align="center">Practice Rust with challenging examples, exercises and projects</p>

16
solutions/basic-types/char-bool.md
View File

@ -1,28 +1,32 @@
1.
```rust
use std::mem::size_of_val;
fn main() {
let c1 = 'a';
assert_eq!(size_of_val(&c1),4);
assert_eq!(size_of_val(&c1), 4);
let c2 = '中';
assert_eq!(size_of_val(&c2),4);
assert_eq!(size_of_val(&c2), 4);
}
```
2.
```rust
fn main() {
let c1 = '中';
print_char(c1);
}
}
fn print_char(c : char) {
fn print_char(c: char) {
println!("{}", c);
}
```
3.
```rust
fn main() {
let _f: bool = false;
@ -35,6 +39,7 @@ fn main() {
```
4.
```rust
fn main() {
let f = true;
@ -44,6 +49,7 @@ fn main() {
```
5.
```rust
fn main() {
let v0: () = ();
@ -63,8 +69,10 @@ fn explicitly_ret_unit() -> () {
```
6.
```rust
use std::mem::size_of_val;
fn main() {
let unit: () = ();
// unit type does't occupy any memeory space

8
solutions/basic-types/functions.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
// don't modify the following two lines!
@ -14,6 +15,7 @@ fn sum(x: i32, y: i32) -> i32 {
```
2.
```rust
fn main() {
print();
@ -26,6 +28,7 @@ fn print() -> () {
```
3.
```rust
fn main() {
never_return();
@ -44,6 +47,7 @@ fn main() {
use std::thread;
use std::time;
fn never_return() -> ! {
// implement this function, don't modify fn signatures
loop {
@ -55,6 +59,7 @@ fn never_return() -> ! {
```
4.
```rust
fn main() {
println!("Success!");
@ -69,7 +74,7 @@ fn get_option(tp: u8) -> Option<i32> {
// TODO
}
};
never_return_fn()
}
@ -97,6 +102,7 @@ fn never_return_fn() -> ! {
```
5.
```rust
fn main() {
// FILL in the blank

11
solutions/basic-types/numbers.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let x: i32 = 5;
@ -11,6 +12,7 @@ fn main() {
```
2.
```rust
fn main() {
let v: u16 = 38_u8 as u16;
@ -18,6 +20,7 @@ fn main() {
```
3.
```rust
fn main() {
let x = 5;
@ -31,6 +34,7 @@ fn type_of<T>(_: &T) -> String {
```
4.
```rust
fn main() {
assert_eq!(i8::MAX, 127);
@ -39,6 +43,7 @@ fn main() {
```
5.
```rust
fn main() {
let v1 = 247_u8 + 8;
@ -48,6 +53,7 @@ fn main() {
```
6.
```rust
fn main() {
let v = 1_024 + 0xff + 0o77 + 0b1111_1111;
@ -56,6 +62,7 @@ fn main() {
```
7.
```rust
fn main() {
let x = 1_000.000_1; // f64
@ -65,6 +72,7 @@ fn main() {
```
8.
```rust
fn main() {
assert!(0.1_f32+0.2_f32==0.3_f32);
@ -78,6 +86,7 @@ fn main() {
```
9.
```rust
fn main() {
let mut sum = 0;
@ -94,6 +103,7 @@ fn main() {
```
10.
```rust
use std::ops::{Range, RangeInclusive};
fn main() {
@ -103,6 +113,7 @@ fn main() {
```
11.
```rust
fn main() {
// Integer addition

3
solutions/basic-types/statements.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let v = {
@ -23,6 +24,7 @@ fn main() {
```
2.
```rust
fn main() {
let v = {
@ -35,6 +37,7 @@ fn main() {
```
3.
```rust
fn main() {
let s = sum(1 , 2);

29
solutions/collections/Hashmap.md
View File

@ -1,4 +1,5 @@
1.
```rust
// FILL in the blanks and FIX the erros
use std::collections::HashMap;
@ -29,6 +30,7 @@ fn main() {
```
2.
```rust
use std::collections::HashMap;
fn main() {
@ -73,9 +75,11 @@ fn main() {
```
3.
```rust
// FILL in the blanks
use std::collections::HashMap;
fn main() {
// type inference lets us omit an explicit type signature (which
// would be `HashMap<&str, u8>` in this example).
@ -109,6 +113,7 @@ fn random_stat_buff() -> u8 {
```
4.
```rust
use std::collections::HashMap;
@ -144,19 +149,21 @@ fn main() {
```
5.
```rust
use std::collections::HashMap;
fn main() {
let v1 = 10;
let mut m1 = HashMap::new();
m1.insert(v1, v1);
println!("v1 is still usable after inserting to hashmap : {}", v1);
// &str implements Copy trait
let v2 = "hello";
let mut m2 = HashMap::new();
m2.insert(v2, v1);
assert_eq!(v2, "hello");
fn main() {
let v1 = 10;
let mut m1 = HashMap::new();
m1.insert(v1, v1);
println!("v1 is still usable after inserting to hashmap : {}", v1);
// &str implements Copy trait
let v2 = "hello";
let mut m2 = HashMap::new();
m2.insert(v2, v1);
assert_eq!(v2, "hello");
}
```

6
solutions/collections/String.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let mut s: String = String::from("hello, ");
@ -36,6 +37,7 @@ fn borrow_string(s: &str) {
```
2.
```rust
// FILL in the blanks
fn main() {
@ -82,6 +84,7 @@ fn main() {
4.
```rust
fn main() {
let s = String::from("hello, 世界");
@ -102,6 +105,7 @@ fn main() {
```
5.
```rust
// FILL in the blanks
fn main() {
@ -123,6 +127,7 @@ fn main() {
```
6.
```rust
fn main() {
let mut s = String::with_capacity(25);
@ -139,6 +144,7 @@ fn main() {
```
7.
```rust
use std::mem;

27
solutions/collections/Vector.md
View File

@ -1,4 +1,5 @@
1.
1.
```rust
fn main() {
let arr: [u8; 3] = [1, 2, 3];
@ -30,6 +31,7 @@ fn is_vec(v: &Vec<u8>) {}
```
2.
```rust
fn main() {
let mut v1 = Vec::from([1, 2, 4]);
@ -45,7 +47,8 @@ fn main() {
}
```
3.
3.
```rust
fn main() {
// array -> Vec
@ -72,7 +75,8 @@ fn main() {
}
```
4.
4.
```rust,editable
fn main() {
let mut v = Vec::from([1, 2, 3]);
@ -94,7 +98,8 @@ fn main() {
}
```
5.
5.
```rust
// FIX the errors
fn main() {
@ -119,7 +124,8 @@ fn main() {
}
```
6.
6.
```rust
// FIX the errors
fn main() {
@ -155,20 +161,22 @@ fn main() {
}
```
7.
7.
```rust
#[derive(Debug, PartialEq)]
enum IpAddr {
V4(String),
V6(String),
}
fn main() {
// FILL in the blank
let v : Vec<IpAddr>= vec![
let v: Vec<IpAddr> = vec![
IpAddr::V4("127.0.0.1".to_string()),
IpAddr::V6("::1".to_string())
];
// Comparing two enums need to derive the PartialEq trait
assert_eq!(v[0], IpAddr::V4("127.0.0.1".to_string()));
assert_eq!(v[1], IpAddr::V6("::1".to_string()));
@ -177,7 +185,8 @@ fn main() {
}
```
8.
8.
```rust
trait IpAddr {
fn display(&self);

12
solutions/compound-types/array.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let arr: [i32; 5] = [1, 2, 3, 4, 5];
@ -8,12 +9,13 @@ fn main() {
```
2.
```rust
fn main() {
// we can ignore parts of the array type or even the whole type, let the compiler infer it for us
let arr0 = [1, 2, 3];
let arr: [_; 3] = ['a', 'b', 'c'];
// Arrays are stack allocated, `std::mem::size_of_val` return the bytes which array occupies
// A char takes 4 byte in Rust: Unicode char
assert!(std::mem::size_of_val(&arr) == 12);
@ -21,6 +23,7 @@ fn main() {
```
3.
```rust
fn main() {
let list: [i32; 100] = [1; 100];
@ -31,6 +34,7 @@ fn main() {
```
4.
```rust
fn main() {
// fix the error
@ -39,10 +43,11 @@ fn main() {
```
5.
```rust
fn main() {
let arr = ['a', 'b', 'c'];
let ele = arr[0];
assert!(ele == 'a');
@ -50,10 +55,11 @@ fn main() {
```
6.
```rust
fn main() {
let names = [String::from("Sunfei"), "Sunface".to_string()];
// `get` returns an Option<T>, it's safe to use
let name0 = names.get(0).unwrap();

16
solutions/compound-types/enum.md
View File

@ -1,4 +1,5 @@
1.
```rust
enum Number {
Zero,
@ -28,6 +29,7 @@ fn main() {
```
2.
```rust
enum Message {
Quit,
@ -43,6 +45,7 @@ fn main() {
```
3.
```rust
enum Message {
Quit,
@ -63,6 +66,7 @@ fn main() {
```
4.
```rust
#[derive(Debug)]
enum Message {
@ -75,14 +79,14 @@ enum Message {
fn main() {
let msgs: [Message; 3] = [
Message::Quit,
Message::Move{x:1, y:3},
Message::ChangeColor(255,255,0)
Message::Move { x: 1, y: 3 },
Message::ChangeColor(255, 255, 0)
];
for msg in msgs {
show_message(msg)
}
}
}
fn show_message(msg: Message) {
println!("{:?}", msg);
@ -90,6 +94,7 @@ fn show_message(msg: Message) {
```
5.
```rust
fn main() {
let five = Some(5);
@ -113,6 +118,7 @@ fn plus_one(x: Option<i32>) -> Option<i32> {
```
6.
```rust
use crate::List::*;
@ -162,10 +168,10 @@ impl List {
// `format!` is similar to `print!`, but returns a heap
// allocated string instead of printing to the console
format!("{}, {}", head, tail.stringify())
},
}
Nil => {
format!("Nil")
},
}
}
}
}

10
solutions/compound-types/slice.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let arr = [1, 2, 3];
@ -9,18 +10,20 @@ fn main() {
```
2.
```rust
fn main() {
let arr: [char; 3] = ['中', '国', '人'];
let slice = &arr[..2];
// TIPS: slice( reference ) IS NOT an array, if it is an array, then `assert!` will passed: each of the two UTF-8 chars '中' and '国' occupies 3 bytes, 2 * 3 = 6
assert!(std::mem::size_of_val(&slice) == 16);
}
```
3.
```rust
fn main() {
let arr: [i32; 5] = [1, 2, 3, 4, 5];
@ -30,6 +33,7 @@ fn main() {
```
4.
```rust
fn main() {
let s = String::from("hello");
@ -42,6 +46,7 @@ fn main() {
```
5.
```rust
fn main() {
let s = "你好，世界";
@ -52,6 +57,7 @@ fn main() {
```
6.
```rust
fn main() {
let mut s = String::from("hello world");
@ -63,8 +69,8 @@ fn main() {
println!("the first word is: {}", word);
s.clear();
}
fn first_word(s: &str) -> &str {
&s[..1]
}

49
solutions/compound-types/string.md
View File

@ -1,14 +1,16 @@
1.
1.
```rust
fn main() {
let s: &str = "hello, world";
}
```
2.
2.
```rust
fn main() {
let s: Box<str> = "hello, world".into();
let s: Box<str> = "hello, world".into();
greetings(&s)
}
@ -16,6 +18,7 @@ fn main() {
println!("{}",s)
}
```
```rust
fn main() {
let s: Box<&str> = "hello, world".into();
@ -27,7 +30,8 @@ fn greetings(s: &str) {
}
```
3.
3.
```rust
fn main() {
let mut s = String::new();
@ -38,10 +42,11 @@ fn main() {
}
```
4.
4.
```rust
fn main() {
let mut s = String::from("hello");
let mut s = String::from("hello");
s.push(',');
s.push_str(" world");
s += "!";
@ -50,7 +55,8 @@ fn main() {
}
```
5.
5.
```rust
fn main() {
let s = String::from("I like dogs");
@ -61,7 +67,8 @@ fn main() {
}
```
6.
6.
```rust
fn main() {
let s1 = String::from("hello,");
@ -72,10 +79,11 @@ fn main() {
}
```
7.
7.
```rust
fn main() {
let s = "hello, world".to_string();
let s = "hello, world".to_string();
greetings(s)
}
@ -95,29 +103,31 @@ fn greetings(s: String) {
}
```
8.
8.
```rust
fn main() {
let s = "hello, world".to_string();
let s = "hello, world".to_string();
let s1: &str = &s;
}
```
```rust
fn main() {
let s = "hello, world";
let s = "hello, world";
let s1: &str = s;
}
```
```rust
fn main() {
let s = "hello, world".to_string();
let s = "hello, world".to_string();
let s1: String = s;
}
```
9.
9.
```rust
fn main() {
// You can use escapes to write bytes by their hexadecimal values
@ -140,7 +150,8 @@ fn main() {
}
```
10.
10.
```rust
fn main() {
let raw_str = "Escapes don't work here: \x3F \u{211D}";
@ -162,7 +173,8 @@ fn main() {
}
```
11.
11.
```rust
fn main() {
let s1 = String::from("hi,中国");
@ -174,7 +186,8 @@ fn main() {
}
```
12.
12.
```rust
fn main() {
for c in "你好，世界".chars() {

8
solutions/compound-types/struct.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct Person {
name: String,
@ -16,6 +17,7 @@ fn main() {
```
2.
```rust
struct Unit;
trait SomeTrait {
@ -35,6 +37,7 @@ fn do_something_with_unit(u: Unit) { }
```
3.
```rust
struct Color(i32, i32, i32);
struct Point(i32, i32, i32);
@ -52,6 +55,7 @@ fn check_color(p: Point) {
```
4.
```rust
struct Person {
name: String,
@ -72,6 +76,7 @@ fn main() {
```
5.
```rust
struct Person {
name: String,
@ -88,6 +93,7 @@ fn build_person(name: String, age: u8) -> Person {
```
6.
```rust
struct User {
active: bool,
@ -115,6 +121,7 @@ fn set_email(u: User) -> User {
```
7.
```rust
#[derive(Debug)]
struct Rectangle {
@ -136,6 +143,7 @@ fn main() {
```
8.
```rust
#[derive(Debug)]
struct File {

6
solutions/compound-types/tuple.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let _t0: (u8,i16) = (0, -1);
@ -9,6 +10,7 @@ fn main() {
```
2.
```rust
fn main() {
let t = ("i", "am", "sunface");
@ -17,6 +19,7 @@ fn main() {
```
3.
```rust
fn main() {
let too_long_tuple = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12);
@ -25,6 +28,7 @@ fn main() {
```
4.
```rust
fn main() {
let tup = (1, 6.4, "hello");
@ -38,6 +42,7 @@ fn main() {
```
5.
```rust
fn main() {
let (x, y, z);
@ -52,6 +57,7 @@ fn main() {
```
6.
```rust
fn main() {
let (x, y) = sum_multiply((2, 3));

6
solutions/crate-module/crate.md
View File

@ -2,13 +2,14 @@
2. `cargo new --lib hello-package1`
3. `hello-package` has a binary crate named `hello-package`, `src/main.rs` is the crate root.
3. `hello-package` has a binary crate named `hello-package`, `src/main.rs` is the crate root.
`hello-pacakge1` has a library crate named `hello-package1`, `src/lib.rs` is the crate root.
4. `hello-package1`
5.
```shell
# FILL in the blanks
.
@ -20,6 +21,7 @@
```
6.
```shell
# Create a package which contains
# 1. three binary crates: `hello-package`, `main1` and `main2`

9
solutions/crate-module/module.md
View File

@ -1,4 +1,5 @@
1.
```rust
// in lib.rs
mod front_of_house {
@ -21,6 +22,7 @@ mod front_of_house {
```
2.
```rust
// in lib.rs
pub mod front_of_house {
@ -53,6 +55,7 @@ pub fn eat_at_restaurant() {
```
3.
```rust
mod back_of_house {
fn fix_incorrect_order() {
@ -75,9 +78,8 @@ mod back_of_house {
}
```
4.
```rust
// in src/lib.rs
@ -104,7 +106,6 @@ pub fn fix_incorrect_order() {
pub fn cook_order() {}
```
```rust
// in src/front_of_house/mod.rs
@ -136,8 +137,8 @@ pub fn take_payment() {}
fn complain() {}
```
5.
```rust
mod front_of_house;

4
solutions/crate-module/use-pub.md
View File

@ -1,4 +1,5 @@
1.
```rust
use std::fmt::Result;
use std::io::Result as IoResult;
@ -7,6 +8,7 @@ fn main() {}
```
2.
```rust
use std::collections::*;
@ -29,8 +31,8 @@ fn main() {
}
```
3.
3.
```rust
// in lib.rs

1
solutions/fight-compiler/borrowing.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct test {
list: Vec<i32>,

47
solutions/flow-control.md
View File

@ -1,11 +1,12 @@
1.
```rust
fn main() {
let n = 5;
if n < 0 {
println!("{} is negative", n);
} else if n > 0 {
} else if n > 0 {
println!("{} is positive", n);
} else {
println!("{} is zero", n);
@ -14,6 +15,7 @@ fn main() {
```
2.
```rust
fn main() {
let n = 5;
@ -26,7 +28,7 @@ fn main() {
} else {
println!(", and is a big number, halve the number");
n / 2
n / 2
};
println!("{} -> {}", n, big_n);
@ -34,9 +36,10 @@ fn main() {
```
3.
```rust
fn main() {
for n in 1..100 {
for n in 1..100 {
if n == 100 {
panic!("NEVER LET THIS RUN")
}
@ -45,9 +48,10 @@ fn main() {
```
4.
```rust
fn main() {
let names = [String::from("liming"),String::from("hanmeimei")];
let names = [String::from("liming"), String::from("hanmeimei")];
for name in &names {
// do something with name...
}
@ -59,24 +63,26 @@ fn main() {
for n in numbers {
// do something with name...
}
println!("{:?}", numbers);
}
```
5.
```rust
fn main() {
let a = [4, 3, 2, 1];
// iterate the indexing and value in 'a'
for (i,v) in a.iter().enumerate() {
println!("The {}th element is {}",i+1,v);
for (i, v) in a.iter().enumerate() {
println!("The {}th element is {}", i + 1, v);
}
}
```
6.
```rust
fn main() {
// A counter variable
@ -98,19 +104,20 @@ fn main() {
n += 1;
}
println!("n reached {}, soloop is over",n);
println!("n reached {}, soloop is over", n);
}
```
7.
```rust
fn main() {
let mut n = 0;
for i in 0..=100 {
if n == 66 {
break
}
n += 1;
if n == 66 {
break;
}
n += 1;
}
assert_eq!(n, 66);
@ -118,16 +125,17 @@ fn main() {
```
8.
```rust
fn main() {
let mut n = 0;
for i in 0..=100 {
if n != 66 {
n+=1;
continue;
}
break
if n != 66 {
n += 1;
continue;
}
break;
}
assert_eq!(n, 66);
@ -135,6 +143,7 @@ fn main() {
```
9.
```rust
fn main() {
let mut count = 0u32;
@ -166,6 +175,7 @@ fn main() {
```
10.
```rust
fn main() {
let mut counter = 0;
@ -183,6 +193,7 @@ fn main() {
```
11.
```rust
fn main() {
let mut count = 0;

6
solutions/formatted-output/debug-display.md
View File

@ -1,4 +1,5 @@
1.
```rust
#[derive(Debug)]
struct Structure(i32);
@ -10,7 +11,9 @@ fn main() {
println!("Now {:?} will print!", Structure(3));
}
```
2.
```rust
#[derive(Debug)]
struct Person {
@ -26,6 +29,7 @@ fn main() {
```
3.
```rust
use std::fmt;
@ -48,6 +52,7 @@ fn main() {
```
4
```rust
use std::fmt;
@ -79,6 +84,7 @@ fn main() {
```
5.
```rust
use std::fmt; // Import the `fmt` module.

9
solutions/formatted-output/formatting.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
println!("{0}, this is {1}. {1}, this is {0}", "Alice", "Bob");// => Alice, this is Bob. Bob, this is Alice
@ -9,6 +10,7 @@ fn main() {
```
2.
```rust
fn main() {
println!("{argument}", argument = "test"); // => "test"
@ -24,6 +26,7 @@ fn main() {
```
3.
```rust
fn main() {
// the following two are padding with 5 spaces
@ -38,6 +41,7 @@ fn main() {
```
4.
```rust
fn main() {
// left align
@ -55,6 +59,7 @@ fn main() {
```
5.
```rust
fn main() {
println!("Hello {:5}!", 5); // => Hello 5!
@ -69,6 +74,7 @@ fn main() {
```
6.
```rust
fn main() {
let v = 3.1415926;
@ -84,6 +90,7 @@ fn main() {
```
7.
```rust
fn main() {
let s = "Hello, world!";
@ -97,6 +104,7 @@ fn main() {
```
8.
```rust
fn main() {
assert_eq!(format!("{:#b}", 27), "0b11011");
@ -113,6 +121,7 @@ fn main() {
```
9.
```rust
fn get_person() -> String {
String::from("sunface")

2
solutions/formatted-output/println.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let s1 = "hello";
@ -9,6 +10,7 @@ fn main() {
```
2.
```rust
fn main() {
print!("hello world, ");

13
solutions/functional-programing/closure.md
View File

@ -1,4 +1,5 @@
1、
```rust
fn main() {
let color = String::from("green");
@ -13,6 +14,7 @@ fn main() {
```
2、
```rust
fn main() {
let mut count = 0;
@ -38,6 +40,7 @@ fn main() {
```
3、
```rust
fn main() {
// A non-copy type.
@ -83,6 +86,7 @@ fn take<T>(_v: &T) {
```
4、
```rust
fn main() {
let example_closure = |x| x;
@ -95,6 +99,7 @@ fn main() {
```
5、
```rust
fn fn_once<F>(func: F)
where
@ -126,11 +131,12 @@ fn main() {
```
6、
```rust
fn main() {
let mut s = String::new();
let update_string = |str| s.push_str(str);
let update_string = |str| s.push_str(str);
exec(update_string);
@ -143,6 +149,7 @@ fn exec<'a, F: FnMut(&'a str)>(mut f: F) {
```
7、
```rust
// A function which takes a closure as an argument and calls it.
// <F> denotes that F is a "Generic type parameter"
@ -197,6 +204,7 @@ fn main() {
```
8、
```rust
fn main() {
let mut s = String::new();
@ -212,6 +220,7 @@ fn exec<'a, F: FnOnce(&'a str) -> String>(mut f: F) {
```
9、
```rust
// Define a function which takes a generic `F` argument
// bounded by `Fn`, and calls it
@ -234,6 +243,7 @@ fn main() {
```
10、
```rust
/* Fill in the blank and fix the errror */
// You can aslo use `impl FnOnce(i32) -> i32`
@ -268,6 +278,7 @@ fn main() {
```
11、
```rust
// Every closure has its own type. Even if one closure has the same representation as another, their types are different.
fn factory(x:i32) -> Box<dyn Fn(i32) -> i32> {

12
solutions/functional-programing/iterator.md
View File

@ -1,4 +1,5 @@
1、
```rust
fn main() {
let arr = [0; 10];
@ -9,6 +10,7 @@ fn main() {
```
2、
```rust
fn main() {
let mut v = Vec::new();
@ -21,6 +23,7 @@ fn main() {
```
3、
```rust
fn main() {
let v1 = vec![1, 2];
@ -48,6 +51,7 @@ fn main() {
```
4、
```rust
fn main() {
let arr = vec![0; 10];
@ -60,6 +64,7 @@ fn main() {
```
5、
```rust
fn main() {
let mut names = vec!["Bob", "Frank", "Ferris"];
@ -76,6 +81,7 @@ fn main() {
```
6、
```rust
fn main() {
let mut values = vec![1, 2, 3];
@ -90,6 +96,7 @@ fn main() {
```
7、
```rust
struct Fibonacci {
curr: u32,
@ -136,6 +143,7 @@ fn main() {
```
8、
```rust
fn main() {
let v1 = vec![1, 2, 3];
@ -152,6 +160,7 @@ fn main() {
```
9、
```rust
use std::collections::HashMap;
fn main() {
@ -169,6 +178,7 @@ fn main() {
```
10、
```rust
fn main() {
let v1: Vec<i32> = vec![1, 2, 3];
@ -180,6 +190,7 @@ fn main() {
```
11、
```rust
use std::collections::HashMap;
fn main() {
@ -192,6 +203,7 @@ fn main() {
```
12、
```rust
#[derive(PartialEq, Debug)]
struct Shoe {

5
solutions/generics-traits/advanced-trait.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct Container(i32, i32);
@ -53,6 +54,7 @@ fn main() {
```
2.
```rust
impl<T: Sub<Output = T>> Sub<Point<T>> for Point<T> {
type Output = Self;
@ -93,6 +95,7 @@ impl<T: Sub<Output = T>> Sub for Point<T> {
```
3.
```rust
trait Pilot {
fn fly(&self) -> String;
@ -134,6 +137,7 @@ fn main() {
```
4.
```rust
trait Person {
fn name(&self) -> String;
@ -209,6 +213,7 @@ fn main() {
```
5.
```rust
use std::fmt;

7
solutions/generics-traits/const-generics.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct Array<T, const N: usize> {
data : [T; N]
@ -20,6 +21,7 @@ fn main() {
```
2.
```rust
fn print_array<T: std::fmt::Debug, const N: usize>(arr: [T; N]) {
println!("{:?}", arr);
@ -33,7 +35,8 @@ fn main() {
}
```
3.
3.
```rust
#![allow(incomplete_features)]
#![feature(generic_const_exprs)]
@ -50,7 +53,7 @@ fn main() {
check_size([0u8; 767]);
check_size([0i32; 191]);
check_size(["hello你好"; 47]); // &str is a string reference, containing a pointer and string length in it, so it takes two word long, in x86-64, 1 word = 8 bytes
check_size(["hello你好".to_string(); 31]); // String is a smart pointer struct, it has three fields: pointer, length and capacity, each takes 8 bytes
check_size([(); 31].map(|_| "hello你好".to_string())); // String is a smart pointer struct, it has three fields: pointer, length and capacity, each takes 8 bytes
check_size(['中'; 191]); // A char takes 4 bytes in Rust
}

8
solutions/generics-traits/generics.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct A; // Concrete type `A`.
struct S(A); // Concrete type `S`.
@ -27,6 +28,7 @@ fn main() {
```
2.
```rust
fn sum<T:std::ops::Add<Output = T>>(x: T, y: T) -> T {
x + y
@ -39,8 +41,8 @@ fn main() {
}
```
3.
```rust
struct Point<T> {
x: T,
@ -54,6 +56,7 @@ fn main() {
```
4.
```rust
// modify this struct to make the code work
struct Point<T, U> {
@ -68,6 +71,7 @@ fn main() {
```
5.
```rust
struct Val<T> {
val: T,
@ -88,6 +92,7 @@ fn main() {
```
6.
```rust
struct Point<T, U> {
x: T,
@ -115,6 +120,7 @@ fn main() {
```
7.
```rust
struct Point<T> {
x: T,

5
solutions/generics-traits/trait-object.md
View File

@ -1,4 +1,5 @@
1.
```rust
trait Bird {
fn quack(&self) -> String;
@ -58,6 +59,7 @@ fn hatch_a_bird(species: u8) ->Box<dyn Bird> {
```
2.
```rust
trait Bird {
fn quack(&self);
@ -101,6 +103,7 @@ fn main() {
```
3.
```rust
trait Draw {
fn draw(&self) -> String;
@ -139,6 +142,7 @@ fn draw_with_ref(x: &dyn Draw) {
```
4.
```rust
trait Foo {
fn method(&self) -> String;
@ -174,6 +178,7 @@ fn main() {
```
5.
```rust
trait MyTrait {
fn f(&self) -> Self;

9
solutions/generics-traits/traits.md
View File

@ -1,4 +1,5 @@
1.
```rust
trait Hello {
fn say_hi(&self) -> String {
@ -37,6 +38,7 @@ fn main() {
```
2.
```rust
// `Centimeters`, a tuple struct that can be compared
#[derive(PartialEq, PartialOrd)]
@ -84,6 +86,7 @@ fn main() {
```
3.
```rust
use std::ops;
@ -101,6 +104,7 @@ fn main() {
```
4.
```rust
use std::ops;
@ -141,6 +145,7 @@ fn main() {
```
5.
```rust
// implement `fn summary` to make the code work
// fix the errors without removing any code line
@ -197,6 +202,7 @@ fn summary(t: &impl Summary) {
```
6.
```rust
struct Sheep {}
struct Cow {}
@ -272,6 +278,7 @@ fn main() {
```
7.
```rust
fn main() {
assert_eq!(sum(1, 2), 3);
@ -298,6 +305,7 @@ where
```
8.
```rust
struct Pair<T> {
x: T,
@ -337,6 +345,7 @@ fn main() {
```
9.
```rust
fn example1() {
// `T: Trait` is the commonly used way

13
solutions/lifetime/advance.md
View File

@ -1,4 +1,5 @@
1、
```rust
struct DoubleRef<'a,'b:'a, T> {
r: &'a T,
@ -9,8 +10,8 @@ fn main() {
}
```
2、
```rust
struct ImportantExcerpt<'a> {
part: &'a str,
@ -29,6 +30,7 @@ fn main() {
```
3、
```rust
fn f<'a, 'b>(x: &'a i32, mut y: &'b i32) where 'a: 'b {
y = x; // &'a i32 is a subtype of &'b i32 because 'a: 'b
@ -39,8 +41,8 @@ fn main() {
}
```
4、
```rust
fn call_on_ref_zero<F>(f: F) where for<'a> F: Fn(&'a i32) {
let zero = 0;
@ -52,7 +54,9 @@ fn main() {
}
```
Higher-ranked lifetimes may also be specified just before the trait: the only difference is the scope of the lifetime parameter, which extends only to the end of the following trait instead of the whole bound. This function is equivalent to the last one.
Higher-ranked lifetimes may also be specified just before the trait: the only difference is the scope of the lifetime
parameter, which extends only to the end of the following trait instead of the whole bound. This function is equivalent
to the last one.
```rust
fn call_on_ref_zero<F>(f: F) where F: for<'a> Fn(&'a i32) {
@ -62,6 +66,7 @@ fn call_on_ref_zero<F>(f: F) where F: for<'a> Fn(&'a i32) {
```
5、
```rust
fn main() {
let mut data = 10;
@ -75,8 +80,8 @@ fn main() {
}
```
6、
```rust
struct Interface<'b, 'a: 'b> {
manager: &'b mut Manager<'a>

14
solutions/lifetime/basic.md
View File

@ -1,5 +1,7 @@
# Lifetime
1.
```rust
fn main() {
let i = 3; // Lifetime for `i` starts. ────────────────┐
@ -20,8 +22,8 @@ fn main() {
} // Lifetime ends. ─────────────────────────────────────┘
```
2. We can't borrow a item whose lifetime is smaller.
```rust
fn main() {
{
@ -38,6 +40,7 @@ fn main() {
```
3
```rust
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
if x.len() > y.len() {
@ -51,6 +54,7 @@ fn main() {}
```
4.
```rust
fn invalid_output() -> String {
String::from("foo")
@ -76,6 +80,7 @@ fn main() {}
```
5.
```rust
fn print_refs<'a, 'b>(x: &'a i32, y: &'b i32) {
println!("x is {} and y is {}", x, y);
@ -98,6 +103,7 @@ fn main() {
```
6.
```rust
// A type `Borrowed` which houses a reference to an
// `i32`. The reference to `i32` must outlive `Borrowed`.
@ -135,6 +141,7 @@ fn main() {
```
7. 🌟
```rust,editable
/* Make it work */
@ -165,8 +172,8 @@ fn main()
}
```
8. 🌟
```rust,editable
#[derive(Debug)]
@ -193,6 +200,7 @@ fn main()
```
9.
```rust
struct ImportantExcerpt<'a> {
part: &'a str,
@ -207,8 +215,8 @@ impl<'a> ImportantExcerpt<'a> {
fn main() {}
```
10.
```rust
fn nput(x: &i32) {

4
solutions/lifetime/static.md
View File

@ -1,4 +1,5 @@
1、
```rust
fn main() {
let v: &str = "hello";
@ -26,6 +27,7 @@ fn need_static(r : &'static str) {
```
2、
```rust
#[derive(Debug)]
struct Config {
@ -54,6 +56,7 @@ fn main() {
```
3、
```rust
fn main() {
// Make a `string` literal and print it:
@ -65,6 +68,7 @@ fn main() {
```
5、
```rust
use std::fmt::Debug;

18
solutions/method.md
View File

@ -1,4 +1,5 @@
1.
```rust
struct Rectangle {
width: u32,
@ -19,6 +20,7 @@ fn main() {
```
2.
```rust
#[derive(Debug)]
struct TrafficLight {
@ -26,12 +28,13 @@ struct TrafficLight {
}
impl TrafficLight {
pub fn show_state(&self) {
pub fn show_state(&self) {
println!("the current state is {}", self.color);
}
}
fn main() {
let light = TrafficLight{
let light = TrafficLight {
color: "red".to_owned(),
};
// Don't take the ownership of `light` here
@ -42,6 +45,7 @@ fn main() {
```
3.
```rust
struct TrafficLight {
color: String,
@ -49,7 +53,7 @@ struct TrafficLight {
impl TrafficLight {
// using `Self` to fill in the blank
pub fn show_state(self: &Self) {
pub fn show_state(self: &Self) {
println!("the current state is {}", self.color);
}
@ -58,10 +62,12 @@ impl TrafficLight {
self.color = "green".to_string()
}
}
fn main() {}
```
4.
```rust
#[derive(Debug)]
struct TrafficLight {
@ -82,6 +88,7 @@ impl TrafficLight {
&self.color
}
}
fn main() {
let light = TrafficLight::new();
assert_eq!(light.get_state(), "red");
@ -89,6 +96,7 @@ fn main() {
```
5.
```rust
struct Rectangle {
width: u32,
@ -107,10 +115,12 @@ impl Rectangle {
self.width > other.width && self.height > other.height
}
}
fn main() {}
```
6.
```rust
#[derive(Debug)]
enum TrafficLightColor {
@ -135,6 +145,6 @@ fn main() {
assert_eq!(c.color(), "yellow");
println!("{:?}",c);
println!("{:?}", c);
}
```

29
solutions/newtype-sized.md
View File

@ -1,4 +1,5 @@
1、
```rust
use std::fmt;
@ -17,6 +18,7 @@ fn main() {
```
2、
```rust
struct Meters(u32);
@ -30,6 +32,7 @@ fn main() {
```
3、
```rust
struct Years(i64);
@ -62,11 +65,13 @@ fn main() {
```
4、Sometimes `newtype` pattern can provide extra readability.
```rust
use std::ops::Add;
use std::fmt::{self, format};
struct Meters(u32);
impl fmt::Display for Meters {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "There are still {} meters left", self.0)
@ -80,9 +85,10 @@ impl Add for Meters {
Self(self.0 + other.0)
}
}
fn main() {
let d = calculate_distance(Meters(10), Meters(20));
assert_eq!(format!("{}",d), "There are still 30 meters left");
assert_eq!(format!("{}", d), "There are still 30 meters left");
}
/* implement calculate_distance */
@ -92,6 +98,7 @@ fn calculate_distance(d1: Meters, d2: Meters) -> Meters {
```
5、
```rust
enum VeryVerboseEnumOfThingsToDoWithNumbers {
Add,
@ -109,6 +116,7 @@ fn main() {
```
6、
```rust
enum VeryVerboseEnumOfThingsToDoWithNumbers {
Add,
@ -124,12 +132,11 @@ impl VeryVerboseEnumOfThingsToDoWithNumbers {
}
}
fn main() {
}
fn main() {}
```
7、
```rust
fn my_function<const N: usize>() -> [u32; N] {
[123; N]
@ -137,11 +144,12 @@ fn my_function<const N: usize>() -> [u32; N] {
fn main() {
let arr = my_function::<5>();
println!("{:?}",arr);
println!("{:?}", arr);
}
```
8、
```rust
fn main() {
let s: &str = "Hello there!";
@ -150,13 +158,14 @@ fn main() {
}
```
9、
```rust
use std::fmt::Display;
fn foobar_1(thing: &dyn Display) {}
fn foobar_2(thing: Box<dyn Display>) {}
fn main() {
}
fn foobar_1(thing: &dyn Display) {}
fn foobar_2(thing: Box<dyn Display>) {}
fn main() {}
```

33
solutions/ownership/borrowing.md
View File

@ -1,4 +1,5 @@
1.
1.
```rust
fn main() {
let x = 5;
@ -9,7 +10,8 @@ fn main() {
}
```
2.
2.
```rust
fn main() {
let x = 5;
@ -20,7 +22,8 @@ fn main() {
}
```
3.
3.
```rust
fn main() {
let mut s = String::from("hello, ");
@ -31,7 +34,8 @@ fn main() {
fn borrow_object(s: &String) {}
```
4.
4.
```rust
fn main() {
let mut s = String::from("hello, ");
@ -44,7 +48,8 @@ fn push_str(s: &mut String) {
}
```
5.
5.
```rust
fn main() {
let mut s = String::from("hello, ");
@ -56,7 +61,8 @@ fn main() {
}
```
6.
6.
```rust
fn main() {
let c = '中';
@ -77,7 +83,8 @@ fn get_addr(r: &char) -> String {
}
```
7.
7.
```rust
fn main() {
let s = String::from("hello");
@ -89,7 +96,8 @@ fn main() {
}
```
8.
8.
```rust
fn main() {
//fix error by modifying this line
@ -101,7 +109,8 @@ fn main() {
fn borrow_object(s: &mut String) {}
```
9.
9.
```rust
fn main() {
let mut s = String::from("hello, ");
@ -114,7 +123,8 @@ fn main() {
fn borrow_object(s: &String) {}
```
10.
10.
```rust
fn main() {
let mut s = String::from("hello, ");
@ -128,7 +138,8 @@ fn main() {
}
```
11.
11.
```rust
fn main() {
let mut s = String::from("hello, ");

9
solutions/ownership/ownership.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let x = String::from("hello, world");
@ -32,6 +33,7 @@ fn main() {
```
2.
```rust
// Don't modify code in main!
fn main() {
@ -49,6 +51,7 @@ fn take_ownership(s: String) -> String {
```
3.
```rust
fn main() {
let s = give_ownership();
@ -78,6 +81,7 @@ fn give_ownership() -> String {
```
4.
```rust
fn main() {
let s = String::from("hello, world");
@ -93,6 +97,7 @@ fn print_str(s: String) {
```
5.
```rust
fn main() {
let x = (1, 2, (), "hello");
@ -102,6 +107,7 @@ fn main() {
```
6.
```rust
fn main() {
let s = String::from("hello, ");
@ -114,6 +120,7 @@ fn main() {
```
7.
```rust
fn main() {
let x = Box::new(5);
@ -127,6 +134,7 @@ fn main() {
```
8.
```rust
fn main() {
let t = (String::from("hello"), String::from("world"));
@ -139,6 +147,7 @@ fn main() {
```
9.
```rust
fn main() {
let t = (String::from("hello"), String::from("world"));

13
solutions/pattern-match/match.md
View File

@ -1,4 +1,5 @@
1.
```rust
enum Direction {
East,
@ -20,6 +21,7 @@ fn main() {
```
2.
```rust
fn main() {
let boolean = true;
@ -38,6 +40,7 @@ fn main() {
```
3.
```rust
enum Message {
Quit,
@ -68,24 +71,26 @@ fn show_message(msg: Message) {
assert_eq!(g, 255);
assert_eq!(b, 0);
}
__ => println!("no data in these variants")
_ => println!("no data in these variants")
}
}
```
4.
```rust
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!(matches!(ab, 'a'..='z' | 'A'..='Z' | '0' | '9'))
assert!(matches!(ab, 'a'..='z' | 'A'..='Z' | '0'..='9'))
}
}
```
5.
```rust
enum MyEnum {
Foo,
@ -107,6 +112,7 @@ fn main() {
```
6.
```rust
fn main() {
let o = Some(7);
@ -118,6 +124,7 @@ fn main() {
```
7.
```rust
enum Foo {
Bar(u8)
@ -133,6 +140,7 @@ fn main() {
```
8.
```rust
enum Foo {
Bar,
@ -152,6 +160,7 @@ fn main() {
```
9.
```rust
fn main() {
let age = Some(30);

6
solutions/pattern-match/patterns.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {}
fn match_number(n: i32) {
@ -19,6 +20,7 @@ fn match_number(n: i32) {
```
2.
```rust
struct Point {
@ -40,6 +42,7 @@ fn main() {
```
3.
```rust
enum Message {
Hello { id: i32 },
@ -61,6 +64,7 @@ fn main() {
```
4.
```rust
fn main() {
let num = Some(4);
@ -74,6 +78,7 @@ fn main() {
```
5.
```rust
fn main() {
let numbers = (2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048);
@ -88,6 +93,7 @@ fn main() {
```
6.
```rust
fn main() {
let mut v = String::from("hello,");

16
solutions/result-panic/panic.md
View File

@ -1,4 +1,5 @@
1.
```rust
use core::panic;
@ -20,21 +21,24 @@ fn main() {
```
2.
```rust
// MAKE the code work by fixing all panics
fn main() {
assert_eq!("abc".as_bytes(), [96, 97, 98]);
assert_eq!("abc".as_bytes(), [97, 98, 99]);
let v = vec![1, 2, 3];
let ele = v[3];
let ele = v[2];
// unwrap may panic when get return a None
let ele = v.get(3).unwrap();
let ele = v.get(2).unwrap();
// Sometimes, the compiler is unable to find the overflow errors for you in compile time ,so a panic will occur
let v = production_rate_per_hour(2);
// because of the same reason as above, we have to wrap it in a function to make the panic occur
divide(15, 0)
divide(15, 1);
println!("Success!")
}
fn divide(x:u8, y:u8) {
@ -42,7 +46,7 @@ fn divide(x:u8, y:u8) {
}
fn production_rate_per_hour(speed: u8) -> f64 {
let cph: u8 = 221;
let cph: u8 = 21;
match speed {
1..=4 => (speed * cph) as f64,
5..=8 => (speed * cph) as f64 * 0.9,
@ -54,4 +58,4 @@ fn production_rate_per_hour(speed: u8) -> f64 {
pub fn working_items_per_minute(speed: u8) -> u32 {
(production_rate_per_hour(speed) / 60 as f64) as u32
}
```
```

6
solutions/result-panic/result.md
View File

@ -1,4 +1,5 @@
1.
```rust
use std::num::ParseIntError;
@ -20,6 +21,7 @@ fn main() {
```
2.
```rust
use std::num::ParseIntError;
@ -38,6 +40,7 @@ fn main() {
```
3.
```rust
use std::fs::File;
use std::io::{self, Read};
@ -71,6 +74,7 @@ fn main() {
```
4.
```rust
use std::num::ParseIntError;
@ -100,6 +104,7 @@ fn main() {
```
5.
```rust
use std::num::ParseIntError;
@ -149,6 +154,7 @@ fn main() {
```
6.
```rust
use std::num::ParseIntError;

5
solutions/type-conversions/as.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
let decimal = 97.123_f32;
@ -13,6 +14,7 @@ fn main() {
```
2.
```rust
// Suppress all warnings from casts which overflow.
#![allow(overflowing_literals)]
@ -24,6 +26,7 @@ fn main() {
```
3.
```rust
fn main() {
assert_eq!(1000 as u16, 1000);
@ -58,6 +61,7 @@ fn main() {
```
4.
```rust
fn main() {
let mut values: [i32; 2] = [1, 2];
@ -75,6 +79,7 @@ fn main() {
```
5.
```rust
fn main() {
let arr :[u64; 13] = [0; 13];

5
solutions/type-conversions/from-into.md
View File

@ -1,4 +1,5 @@
1.
```rust
fn main() {
// impl From<bool> for i32
@ -28,6 +29,7 @@ fn main() {
```
2.
```rust
// From is now included in `std::prelude`, so there is no need to introduce it into the current scope
// use std::convert::From;
@ -56,6 +58,7 @@ fn main() {
```
3.
```rust
use std::fs;
use std::io;
@ -92,6 +95,7 @@ fn main() {
```
4.
```rust
fn main() {
let n: i16 = 256;
@ -111,6 +115,7 @@ fn main() {
```
5.
```rust,editable
#[derive(Debug, PartialEq)]
struct EvenNum(i32);

3
solutions/type-conversions/others.md
View File

@ -1,4 +1,5 @@
1
```rust
use std::fmt;
@ -23,6 +24,7 @@ fn main() {
```
2.
```rust
// To use `from_str` method, you needs to introduce this trait into the current scope.
use std::str::FromStr;
@ -38,6 +40,7 @@ fn main() {
```
3.
```rust
use std::str::FromStr;
use std::num::ParseIntError;

51
solutions/variables.md
View File

@ -1,23 +1,26 @@
1.
1.
```rust
fn main() {
let x: i32 = 5; // uninitialized but using, ERROR !
let y: i32; // uninitialized but also unusing, only warning
println!("{} is equal to 5", x);
println!("{} is equal to 5", x);
}
```
2.
```rust
fn main() {
let mut x = 1;
x += 2;
println!("{} is equal to 3", x);
let mut x = 1;
x += 2;
println!("{} is equal to 3", x);
}
```
3.
```rust
fn main() {
let x: i32 = 10;
@ -25,15 +28,16 @@ fn main() {
let y: i32 = 5;
println!("The value of x is {} and value of y is {}", x, y);
}
println!("The value of x is {}", x);
println!("The value of x is {}", x);
}
```
4.
```rust
fn main() {
let x = define_x();
println!("{}, world", x);
println!("{}, world", x);
}
fn define_x() -> String {
@ -42,7 +46,20 @@ fn define_x() -> String {
}
```
```rust
fn main() {
let x = define_x();
println!("{:?}, world", x);
}
fn define_x() -> &'static str {
let x = "hello";
x
}
```
5.
```rust
fn main() {
let x: i32 = 5;
@ -53,42 +70,45 @@ fn main() {
assert_eq!(x, 5);
let x = 42;
let x = 42;
println!("{}", x); // Prints "42".
}
```
6.
```rust
fn main() {
let mut x: i32 = 1;
x = 7;
// shadowing and re-binding
let x = x;
let x = x;
// x += 3;
let y = 4;
// shadowing
let y = "I can also be bound to text!";
let y = "I can also be bound to text!";
}
```
7.
```rust
fn main() {
let _x = 1;
let _x = 1;
}
```
```rust
#[allow(unused_variables)]
fn main() {
let x = 1;
let x = 1;
}
```
8.
```rust
fn main() {
let (mut x, y) = (1, 2);
@ -110,12 +130,13 @@ fn main() {
```
9.
```rust
fn main() {
let (x, y);
(x,..) = (3, 4);
(x, ..) = (3, 4);
[.., y] = [1, 2];
// fill the blank to make the code work
assert_eq!([x,y], [3,2]);
assert_eq!([x, y], [3, 2]);
}
```

4
zh-CN/src/SUMMARY.md
View File

@ -45,8 +45,8 @@
- [模块 Module](crate-module/module.md)
- [使用use引入模块及受限可见性](crate-module/use-pub.md)
- [注释和文档](comments-docs.md)
- [格式化输出 todo](formatted-output.md)
- [生命周期 todo](lifetime/intro.md)
- [格式化输出](formatted-output.md)
- [生命周期](lifetime/intro.md)
- [生命周期基础](lifetime/basic.md)
- [&'static 和 T: 'static](lifetime/static.md)
- [深入生命周期](lifetime/advance.md)

11
zh-CN/src/basic-types/char-bool-unit.md
View File

@ -3,6 +3,7 @@
### 字符
1. 🌟
```rust, editable
// 修改2处 `assert_eq!` 让代码工作
use std::mem::size_of_val;
fn main() {
@ -18,7 +19,7 @@ fn main() {
2. 🌟
```rust, editable
// 修改一行让代码正常打印
fn main() {
let c1 = "中";
print_char(c1);
@ -33,7 +34,7 @@ fn print_char(c : char) {
3. 🌟
```rust, editable
// make println! work
// 使成功打印
fn main() {
let _f: bool = false;
@ -72,12 +73,12 @@ fn main() {
}
fn implicitly_ret_unit() {
println!("I will returen a ()")
println!("I will return a ()")
}
// 不要使用下面的函数，它只用于演示！
fn explicitly_ret_unit() -> () {
println!("I will returen a ()")
println!("I will return a ()")
}
```
@ -94,4 +95,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/basic-types/char-bool.md)找到答案(在 solutions 路径下)

2
zh-CN/src/basic-types/functions.md
View File

@ -90,4 +90,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/basic-types/functions.md)找到答案(在 solutions 路径下)

2
zh-CN/src/basic-types/numbers.md
View File

@ -163,4 +163,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/basic-types/numbers.md)找到答案(在 solutions 路径下)

2
zh-CN/src/basic-types/statements-expressions.md
View File

@ -61,4 +61,4 @@ fn sum(x: i32, y: i32) -> i32 {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/basic-types/statements.md)找到答案(在 solutions 路径下)

2
zh-CN/src/collections/String.md
View File

@ -204,4 +204,4 @@ fn main() {
### 常用方法
关于 String 的常用方法练习，可以查看[这里](../std/String.md).
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/collections/String.md)(under the solutions path), but only use it when you need it

4
zh-CN/src/collections/hashmap.md
View File

@ -140,7 +140,7 @@ fn main() {
(Viking::new("Harald", "Iceland"), 12),
]);
// 使用 derive 的方式来打印 vikong 的当前状态
// 使用 derive 的方式来打印 viking 的当前状态
for (viking, health) in &vikings {
println!("{:?} has {} hp", viking, health);
}
@ -220,4 +220,4 @@ hash.insert(42, "the answer");
assert_eq!(hash.get(&42), Some(&"the answer"));
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/collections/Hashmap.md)(under the solutions path), but only use it when you need it

2
zh-CN/src/collections/vector.md
View File

@ -245,4 +245,4 @@ fn main() {
}
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/collections/Vector.md)(under the solutions path), but only use it when you need it

4
zh-CN/src/compound-types/array.md
View File

@ -1,5 +1,5 @@
# 数组
数组的类型是 `[T; Lengh]`, 就如你所看到的，数组的长度是类型签名的一部分，因此数组的长度必须在编译期就已知，例如你不能使用以下方式来声明一个数组:
数组的类型是 `[T; Length]`，就如你所看到的，数组的长度是类型签名的一部分，因此数组的长度必须在编译期就已知，例如你不能使用以下方式来声明一个数组:
```rust
fn create_arr(n: i32) {
let arr = [1; n];
@ -83,4 +83,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/array.md)找到答案(在 solutions 路径下)

2
zh-CN/src/compound-types/enum.md
View File

@ -191,4 +191,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/enum.md)找到答案(在 solutions 路径下)

2
zh-CN/src/compound-types/slice.md
View File

@ -89,4 +89,4 @@ fn first_word(s: &str) -> &str {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/slice.md)找到答案(在 solutions 路径下)

13
zh-CN/src/compound-types/string.md
View File

@ -20,7 +20,7 @@ fn main() {
// 使用至少两种方法来修复错误
fn main() {
let s: Box<str> = "hello, world".into();
let s: Box<str> = "hello, world".into();
greetings(s)
}
@ -50,7 +50,7 @@ fn main() {
// 修复所有错误，并且不要新增代码行
fn main() {
let s = String::from("hello");
let s = String::from("hello");
s.push(',');
s.push(" world");
s += "!".to_string();
@ -98,7 +98,7 @@ fn main() {
// 使用至少两种方法来修复错误
fn main() {
let s = "hello, world";
let s = "hello, world";
greetings(s)
}
@ -113,7 +113,7 @@ fn greetings(s: String) {
// 使用两种方法来解决错误，不要新增代码行
fn main() {
let s = "hello, world".to_string();
let s = "hello, world".to_string();
let s1: &str = s;
}
```
@ -146,10 +146,9 @@ fn main() {
10. 🌟🌟🌟 有时候需要转义的字符很多，我们会希望使用更方便的方式来书写字符串: raw string.
```rust,editable
/* 填空并修复所有错误 */
fn main() {
let raw_str = r"Escapes don't work here: \x3F \u{211D}";
// 修改以下代码行，让它工作
assert_eq!(raw_str, "Escapes don't work here: ? ℝ");
// 如果你希望在字符串中使用双引号，可以使用以下形式
@ -255,4 +254,4 @@ fn main() {
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/string.md)找到答案(在 solutions 路径下)

2
zh-CN/src/compound-types/struct.md
View File

@ -218,4 +218,4 @@ fn main() {
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/struct.md)找到答案(在 solutions 路径下)

2
zh-CN/src/compound-types/tuple.md
View File

@ -77,4 +77,4 @@ fn sum_multiply(nums: (i32, i32)) -> (i32, i32) {
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/compound-types/tuple.md)找到答案(在 solutions 路径下)

2
zh-CN/src/crate-module/crate.md
View File

@ -108,4 +108,4 @@ edition = "2021"
可以看到，上面的 package 结构非常标准，你可以在很多 Rust 项目中看到该结构的身影。
> You can find the solutions [here](https://github.com/sunface/rust-by-practice) (under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/crate-module/crate.md) (under the solutions path), but only use it when you need it :)

2
zh-CN/src/crate-module/module.md
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@ -192,4 +192,4 @@ fn main() {
}
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice) (under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/crate-module/module.md) (under the solutions path), but only use it when you need it :)

2
zh-CN/src/crate-module/use-pub.md
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@ -67,4 +67,4 @@ pub mod a {
至此，包与模块章节已经结束，关于 `hello-package` 的完整代码可以在[这里](https://github.com/sunface/rust-by-practice/tree/master/practices/hello-package) 找到.
> You can find the solutions [here](https://github.com/sunface/rust-by-practice) (under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/crate-module/use-pub.md) (under the solutions path), but only use it when you need it :)

3
zh-CN/src/elegant-code-base.md
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@ -35,4 +35,7 @@
你也可以在[以下地址](https://github.com/phil-opp/blog_os)找到完整的源代码。
### 7. mini-redis
[mini-redis](https://github.com/tokio-rs/mini-redis) 是一个不完整的 Redis 客户端、服务器实现，由 tokio 官方出品，代码质量非常高，而且有详细的注释，非常适合学习 Rust 和异步编程。
**To be continued...**

2
zh-CN/src/flow-control.md
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@ -242,4 +242,4 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/flow-control.md)找到答案(在 solutions 路径下)

184
zh-CN/src/formatted-output.md
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@ -1 +1,183 @@
# Formatted output
# 格式化输出
## 位置参数
1.🌟🌟
```rust,edtiable
/* 填空 */
fn main() {
println!("{0}, this is {1}. {1}, this is {0}", "Alice", "Bob");// => Alice, this is Bob. Bob, this is Alice
assert_eq!(format!("{1}{0}", 1, 2), __);
assert_eq!(format!(__, 1, 2), "2112");
println!("Success!");
}
```
## 具名参数
2.🌟🌟
```rust,editable
fn main() {
println!("{argument}", argument = "test"); // => "test"
/* 填空 */
assert_eq!(format!("{name}{}", 1, __), "21");
assert_eq!(format!(__,a = "a", b = 'b', c = 3 ), "a 3 b");
/* 修复错误 */
// 具名参数必须放在其它参数后面
println!("{abc} {1}", abc = "def", 2);
println!("Success!")
}
```
## 字符串对齐
3.🌟🌟 默认情况下，通过空格来填充字符串
```rust,editable
fn main() {
// 下面两个都是通过 5 个空格来填充
println!("Hello {:5}!", "x"); // => "Hello x !"
println!("Hello {:1$}!", "x", 5); // => "Hello x !"
/* 填空 */
assert_eq!(format!("Hello __!", 5, "x"), "Hello x !");
assert_eq!(format!("Hello __!", "x", width = 5), "Hello x !");
println!("Success!")
}
```
4.🌟🌟🌟 左对齐, 右对齐, 使用指定的字符填充
```rust,editable
fn main() {
// 左对齐
println!("Hello {:<5}!", "x"); // => Hello x !
// 右对齐
assert_eq!(format!("Hello __!", "x"), "Hello x!");
// 居中对齐
assert_eq!(format!("Hello __!", "x"), "Hello x !");
// 左对齐，并使用 `&` 填充
assert_eq!(format!("Hello {:&<5}!", "x"), __);
println!("Success!")
}
```
5.🌟🌟 我们还能使用 0 来填充数字
```rust,editable
fn main() {
println!("Hello {:5}!", 5); // => Hello 5!
println!("Hello {:+}!", 5); // => Hello +5!
println!("Hello {:05}!", 5); // => Hello 00005!
println!("Hello {:05}!", -5); // => Hello -0005!
/* 填空 */
assert!(format!("{number:0>width$}", number=1, width=6) == __);
println!("Success!")
}
```
## 精度
6.🌟🌟 浮点数精度
```rust,editable
/* 填空 */
fn main() {
let v = 3.1415926;
println!("{:.1$}", v, 4); // same as {:.4} => 3.1416
assert_eq!(format!("__", v), "3.14");
assert_eq!(format!("__", v), "+3.14");
assert_eq!(format!("__", v), "3");
println!("Success!")
}
```
7.🌟🌟🌟 字符串长度
```rust,editable
fn main() {
let s = "Hello, world!";
println!("{0:.5}", s); // => Hello
assert_eq!(format!("Hello __!", 3, "abcdefg"), "Hello abc!");
println!("Success!")
}
```
## 二进制, 八进制, 十六进制
- format!("{}", foo) -> "3735928559"
- format!("0x{:X}", foo) -> "0xDEADBEEF"
- format!("0o{:o}", foo) -> "0o33653337357"
8.🌟🌟
```rust,editable
fn main() {
assert_eq!(format!("__", 27), "0b11011");
assert_eq!(format!("__", 27), "0o33");
assert_eq!(format!("__", 27), "0x1b");
assert_eq!(format!("__", 27), "0x1B");
println!("{:x}!", 27); // 没有前缀的十六进制 => 1b
println!("{:#010b}", 27); // 使用 0 来填充二进制，宽度为 10 => 0b00011011
println!("Success!")
}
```
## 捕获环境中的值
9.🌟🌟🌟
```rust,editable
fn get_person() -> String {
String::from("sunface")
}
fn get_format() -> (usize, usize) {
(4, 1)
}
fn main() {
let person = get_person();
println!("Hello, {person}!");
let (width, precision) = get_format();
let scores = [("sunface", 99.12), ("jack", 60.34)];
/* 让下面的代码输出:
sunface: 99.1
jack: 60.3
*/
for (name, score) in scores {
println!("{name}: __");
}
}
```
## Others
**Example**
```rust,editable
fn main() {
// 指数
println!("{:2e}", 1000000000); // => 1e9
println!("{:2E}", 1000000000); // => 1E9
// 指针地址
let v= vec![1, 2, 3];
println!("{:p}", v.as_ptr()); // => 0x600002324050
// 转义
println!("Hello {{}}"); // => Hello {}
}
```

4
zh-CN/src/generics-traits/advanced-traits.md
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@ -9,7 +9,7 @@ pub trait CacheableItem: Clone + Default + fmt::Debug + Decodable + Encodable {
}
```
相比 `AsRef<[u8]> + Clone + fmt::Debug + Eq + Hash`， `Address` 的使用可以极大的极少其它类型在实现该特征时所需的模版代码.
相比 `AsRef<[u8]> + Clone + fmt::Debug + Eq + Hash`， `Address` 的使用可以极大的减少其它类型在实现该特征时所需的模版代码.
1. 🌟🌟🌟
```rust,editable
@ -268,4 +268,4 @@ fn main() {
}
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/advanced-trait.md)(under the solutions path), but only use it when you need it :)

2
zh-CN/src/generics-traits/const-generics.md
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@ -123,7 +123,7 @@ fn main() {
check_size([0u8; 767]);
check_size([0i32; 191]);
check_size(["hello你好"; __]); // size of &str ?
check_size(["hello你好".to_string(); __]); // size of String?
check_size([(); __].map(|_| "hello你好".to_string())); // size of String?
check_size(['中'; __]); // size of char ?
}

2
zh-CN/src/generics-traits/generics.md
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@ -142,5 +142,5 @@ fn main() {
}
```
> 你可以在[这里](https://github.com/sunface/rust-by-practice)找到答案(在 solutions 路径下)
> 你可以在[这里](https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/generics.md)找到答案(在 solutions 路径下)

2
zh-CN/src/generics-traits/trait-object.md
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@ -223,4 +223,4 @@ fn main() {
}
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/trait-object.md)(under the solutions path), but only use it when you need it :)

8
zh-CN/src/generics-traits/traits.md
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@ -143,8 +143,8 @@ fn main() {
let _one_second = Seconds(1);
println!("One second looks like: {:?}", _one_second);
let _this_is_true = (_one_second == _one_second);
let _this_is_true = (_one_second > _one_second);
let _this_is_true = _one_second == _one_second;
let _this_is_true = _one_second > _one_second;
let foot = Inches(12);
@ -175,7 +175,7 @@ use std::ops;
// 实现 fn multiply 方法
// 如上所述，`+` 需要 `T` 类型实现 `std::ops::Add` 特征
// 那么, `*` 运算符需要实现什么特征呢? 你可以在这里找到答案: https://doc.rust-lang.org/core/ops/
fn multipl
fn multiply
fn main() {
assert_eq!(6, multiply(2u8, 3u8));
@ -467,4 +467,4 @@ fn main() {
}
```
> You can find the solutions [here](https://github.com/sunface/rust-by-practice)(under the solutions path), but only use it when you need it :)
> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/traits.md)(under the solutions path), but only use it when you need it :)

343
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@ -1,26 +1,337 @@
## 生命周期消除
## 生命周期基础
编译器通过生命周期来确保所有的借用都是合法的，典型的，一个变量在创建时生命周期随之开始，销毁时生命周期也随之结束。
## 生命周期的范围
1、 🌟
```rust,editable
/* 为 `i` 和 `borrow2` 标注合适的生命周期范围 */
// `i` 拥有最长的生命周期，因为它的作用域完整的包含了 `borrow1` 和 `borrow2` 。
// 而 `borrow1` 和 `borrow2` 的生命周期并无关联，因为它们的作用域没有重叠
fn main() {
let i = 3;
{
let borrow1 = &i; // `borrow1` 生命周期开始. ──┐
// │
println!("borrow1: {}", borrow1); // │
} // `borrow1` 生命周期结束. ──────────────────────────────────┘
{
let borrow2 = &i;
println!("borrow2: {}", borrow2);
}
}
```
2. 🌟🌟
**示例**
```rust
fn print(s: &str); // elided
fn print<'a>(s: &'a str); // expanded
{
let x = 5; // ----------+-- 'b
// |
let r = &x; // --+-- 'a |
// | |
println!("r: {}", r); // | |
// --+ |
} // ----------+
```
fn debug(lvl: usize, s: &str); // elided
fn debug<'a>(lvl: usize, s: &'a str); // expanded
fn substr(s: &str, until: usize) -> &str; // elided
fn substr<'a>(s: &'a str, until: usize) -> &'a str; // expanded
```rust,editable
/* 像上面的示例一样，为 `r` 和 `x` 标准生命周期，然后从生命周期的角度. */
fn get_str() -> &str; // ILLEGAL
fn main() {
{
let r; // ---------+-- 'a
// |
{ // |
let x = 5; // -+-- 'b |
r = &x; // | |
} // -+ |
// |
println!("r: {}", r); // |
} // ---------+
}
```
fn frob(s: &str, t: &str) -> &str; // ILLEGAL
## 生命周期标注
Rust 的借用检查器使用显式的生命周期标注来确定一个引用的合法范围。但是对于用户来说，我们在大多数场景下，都无需手动去标注生命周期，原因是编译器会在某些情况下自动应用生命周期消除规则。
fn get_mut(&mut self) -> &mut T; // elided
fn get_mut<'a>(&'a mut self) -> &'a mut T; // expanded
在了解编译器使用哪些规则帮我们消除生命周期之前，首先还是需要知道该如何手动标记生命周期。
fn args<T: ToCStr>(&mut self, args: &[T]) -> &mut Command // elided
fn args<'a, 'b, T: ToCStr>(&'a mut self, args: &'b [T]) -> &'a mut Command // expanded
fn new(buf: &mut [u8]) -> BufWriter; // elided
fn new(buf: &mut [u8]) -> BufWriter<'_>; // elided (with `rust_2018_idioms`)
fn new<'a>(buf: &'a mut [u8]) -> BufWriter<'a> // expanded
#### 函数
**大家先忽略生命周期消除规则**，让我们看看，函数签名中的生命周期有哪些限制:
- 需要为每个引用标注上合适的生命周期
- 返回值中的引用，它的生命周期要么跟某个引用参数相同，要么是 `'statc`
**示例**
```rust,editable
// 引用参数中的生命周期 'a 至少要跟函数活得一样久
fn print_one<'a>(x: &'a i32) {
println!("`print_one`: x is {}", x);
}
// 可变引用依然需要标准生命周期
fn add_one<'a>(x: &'a mut i32) {
*x += 1;
}
// 下面代码中，每个参数都拥有自己独立的生命周期，事实上，这个例子足够简单，因此它们应该被标记上相同的生命周期 `'a`，但是对于复杂的例子而言，独立的生命周期标注是可能存在的
fn print_multi<'a, 'b>(x: &'a i32, y: &'b i32) {
println!("`print_multi`: x is {}, y is {}", x, y);
}
// 返回一个通过参数传入的引用是很常见的，但是这种情况下需要标注上正确的生命周期
fn pass_x<'a, 'b>(x: &'a i32, _: &'b i32) -> &'a i32 { x }
fn main() {
let x = 7;
let y = 9;
print_one(&x);
print_multi(&x, &y);
let z = pass_x(&x, &y);
print_one(z);
let mut t = 3;
add_one(&mut t);
print_one(&t);
}
```
3、 🌟
```rust,editable
/* 添加合适的生命周期标注，让下面的代码工作 */
fn longest(x: &str, y: &str) -> &str {
if x.len() > y.len() {
x
} else {
y
}
}
fn main() {}
```
4、🌟🌟🌟
```rust,editable
/* 使用三种方法修复下面的错误 */
fn invalid_output<'a>() -> &'a String {
&String::from("foo")
}
fn main() {
}
```
5、🌟🌟
```rust,editable
// `print_refs` 有两个引用参数，它们的生命周期 `'a` 和 `'b` 至少得跟函数活得一样久
fn print_refs<'a, 'b>(x: &'a i32, y: &'b i32) {
println!("x is {} and y is {}", x, y);
}
/* 让下面的代码工作 */
fn failed_borrow<'a>() {
let _x = 12;
// ERROR: `_x` 活得不够久does not live long enough
let y: &'a i32 = &_x;
// 在函数内使用 `'a` 将会报错，原因是 `&_x` 的生命周期显然比 `'a` 要小
// 你不能将一个小的生命周期强转成大的
}
fn main() {
let (four, nine) = (4, 9);
print_refs(&four, &nine);
// 这里，four 和 nice 的生命周期必须要比函数 print_refs 长
failed_borrow();
// `failed_borrow` 没有传入任何引用去限制生命周期 `'a`，因此，此时的 `'a` 生命周期是没有任何限制的，它默认是 `'static`
}
```
#### Structs
6、 🌟
```rust,editable
/* 增加合适的生命周期标准，让代码工作 */
// `i32` 的引用必须比 `Borrowed` 活得更久
#[derive(Debug)]
struct Borrowed(&i32);
// 类似的，下面两个引用也必须比结构体 `NamedBorrowed` 活得更久
#[derive(Debug)]
struct NamedBorrowed {
x: &i32,
y: &i32,
}
#[derive(Debug)]
enum Either {
Num(i32),
Ref(&i32),
}
fn main() {
let x = 18;
let y = 15;
let single = Borrowed(&x);
let double = NamedBorrowed { x: &x, y: &y };
let reference = Either::Ref(&x);
let number = Either::Num(y);
println!("x is borrowed in {:?}", single);
println!("x and y are borrowed in {:?}", double);
println!("x is borrowed in {:?}", reference);
println!("y is *not* borrowed in {:?}", number);
}
```
7、 🌟🌟
```rust,editable
/* 让代码工作 */
#[derive(Debug)]
struct NoCopyType {}
#[derive(Debug)]
struct Example<'a, 'b> {
a: &'a u32,
b: &'b NoCopyType
}
fn main()
{
let var_a = 35;
let example: Example;
{
let var_b = NoCopyType {};
/* 修复错误 */
example = Example { a: &var_a, b: &var_b };
}
println!("(Success!) {:?}", example);
}
```
8、 🌟🌟
```rust,editable
#[derive(Debug)]
struct NoCopyType {}
#[derive(Debug)]
#[allow(dead_code)]
struct Example<'a, 'b> {
a: &'a u32,
b: &'b NoCopyType
}
/* 修复函数的签名 */
fn fix_me(foo: &Example) -> &NoCopyType
{ foo.b }
fn main()
{
let no_copy = NoCopyType {};
let example = Example { a: &1, b: &no_copy };
fix_me(&example);
println!("Success!")
}
```
## 方法
方法的生命周期标注跟函数类似。
**示例**
```rust,editable
struct Owner(i32);
impl Owner {
fn add_one<'a>(&'a mut self) { self.0 += 1; }
fn print<'a>(&'a self) {
println!("`print`: {}", self.0);
}
}
fn main() {
let mut owner = Owner(18);
owner.add_one();
owner.print();
}
```
9、🌟🌟
```rust,editable
/* 添加合适的生命周期让下面代码工作 */
struct ImportantExcerpt {
part: &str,
}
impl ImportantExcerpt {
fn level(&'a self) -> i32 {
3
}
}
fn main() {}
```
## 生命周期消除( Elision )
有一些生命周期的标注方式很常见，因此编译器提供了一些规则，可以让我们在一些场景下无需去标注生命周期，既节省了敲击键盘的繁琐，又能提升可读性。
这种规则被称为生命周期消除规则( Elision )，该规则之所以存在，仅仅是因为这些场景太通用了，为了方便用户而已。事实上对于借用检查器而言，该有的生命周期一个都不能少，只不过对于用户而言，可以省去一些。
10、🌟🌟
```rust,editable
/* 移除所有可以消除的生命周期标注 */
fn nput<'a>(x: &'a i32) {
println!("`annotated_input`: {}", x);
}
fn pass<'a>(x: &'a i32) -> &'a i32 { x }
fn longest<'a, 'b>(x: &'a str, y: &'b str) -> &'a str {
x
}
struct Owner(i32);
impl Owner {
fn add_one<'a>(&'a mut self) { self.0 += 1; }
fn print<'a>(&'a self) {
println!("`print`: {}", self.0);
}
}
struct Person<'a> {
age: u8,
name: &'a str,
}
enum Either<'a> {
Num(i32),
Ref(&'a i32),
}
fn main() {}
```

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