From bfc30e2024f6024d7b03859e7607a5a28fb32d0b Mon Sep 17 00:00:00 2001
From: sunface <cto@188.com>
Date: Fri, 25 Feb 2022 22:57:13 +0800
Subject: [PATCH] add reference and borrowing

---
 en/src/ownership/borrowing.md    | 165 ++++++++++++++++++++++++++++++
 zh-CN/src/ownership/borrowing.md | 167 ++++++++++++++++++++++++++++++-
 2 files changed, 331 insertions(+), 1 deletion(-)

diff --git a/en/src/ownership/borrowing.md b/en/src/ownership/borrowing.md
index 9ce0535..86ec6e4 100644
--- a/en/src/ownership/borrowing.md
+++ b/en/src/ownership/borrowing.md
@@ -1 +1,166 @@
 # Reference and Borrowing
+
+### Reference
+🌟
+```rust,editable
+
+fn main() {
+   let x = 5;
+   // fill the blank
+   let p = __;
+
+   println!("the memory address of x is {:p}", p); // output: 0x16fa3ac84
+}
+```
+
+🌟
+```rust,editable
+
+fn main() {
+    let x = 5;
+    let y = &x;
+
+    // modify this line only
+    assert_eq!(5, y);
+}
+```
+
+🌟
+```rust,editable
+
+// fix error
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(s)
+}
+
+fn borrow_object(s: &String) {}
+```
+
+🌟
+```rust,editable
+
+// fix error
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(&s)
+}
+
+fn borrow_object(s: &mut String) {}
+```
+
+🌟🌟
+```rust,editable
+
+fn main() {
+    let mut s = String::from("hello, ");
+
+    // fill the blank to make it work
+    let p = __;
+    
+    p.push_str("world");
+}
+```
+
+#### ref
+`ref` can be used to take references to a value, similar to `&`.
+
+🌟🌟🌟
+```rust,editable
+
+fn main() {
+    let c = '中';
+
+    let r1 = &c;
+    // fill the blank，dont change other code
+    let __ r2 = c;
+
+    assert_eq!(*r1, *r2);
+    
+    // check the equality of the two address strings
+    assert_eq!(get_addr(r1),get_addr(r2));
+}
+
+// get memory address string
+fn get_addr(r: &char) -> String {
+    format!("{:p}", r)
+}
+```
+
+### Borrowing rules
+🌟
+```rust,editable
+
+// remove something to make it work
+// don't remove a whole line !
+fn main() {
+    let mut s = String::from("hello");
+
+    let r1 = &mut s;
+    let r2 = &mut s;
+
+    println!("{}, {}", r1, r2);
+}
+```
+
+#### Mutablity
+🌟 Error: Borrow a immutable object as mutable
+```rust,editable
+
+fn main() {
+    //fix error by modifying this line
+    let  s = String::from("hello, ");
+
+    borrow_object(&mut s)
+}
+
+fn borrow_object(s: &mut String) {}
+```
+
+🌟🌟 Ok: Borrow a mutable object as immutable
+```rust,editable
+
+// this code has no errors!
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(&s);
+    
+    s.push_str("world");
+}
+
+fn borrow_object(s: &String) {}
+```
+
+### NLL
+🌟🌟
+```rust,editable
+
+// comment one line to make it work
+fn main() {
+    let mut s = String::from("hello, ");
+
+    let r1 = &mut s;
+    r1.push_str("world");
+    let r2 = &mut s;
+    r2.push_str("!");
+    
+    println!("{}",r1);
+}
+```
+
+🌟🌟🌟
+```rust,editable
+
+fn main() {
+    let mut s = String::from("hello, ");
+
+    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
+}
+```
\ No newline at end of file
diff --git a/zh-CN/src/ownership/borrowing.md b/zh-CN/src/ownership/borrowing.md
index 9ce0535..f78c2be 100644
--- a/zh-CN/src/ownership/borrowing.md
+++ b/zh-CN/src/ownership/borrowing.md
@@ -1 +1,166 @@
-# Reference and Borrowing
+# 引用和借用
+
+### 引用
+🌟
+```rust,editable
+
+fn main() {
+   let x = 5;
+   // 填写空白处
+   let p = __;
+
+   println!("x 的内存地址是 {:p}", p); // output: 0x16fa3ac84
+}
+```
+
+🌟
+```rust,editable
+
+fn main() {
+    let x = 5;
+    let y = &x;
+
+    // 只能修改以下行
+    assert_eq!(5, y);
+}
+```
+
+🌟
+```rust,editable
+
+// 修复错误
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(s)
+}
+
+fn borrow_object(s: &String) {}
+```
+
+🌟
+```rust,editable
+
+// 修复错误
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(&s)
+}
+
+fn borrow_object(s: &mut String) {}
+```
+
+🌟🌟
+```rust,editable
+
+fn main() {
+    let mut s = String::from("hello, ");
+
+    // 填写空白处，让代码工作
+    let p = __;
+    
+    p.push_str("world");
+}
+```
+
+#### ref
+`ref` 与 `&` 类似，可以用来获取一个值的引用，但是它们的用法有所不同。
+
+🌟🌟🌟
+```rust,editable
+
+fn main() {
+    let c = '中';
+
+    let r1 = &c;
+    // 填写空白处，但是不要修改其它行的代码
+    let __ r2 = c;
+
+    assert_eq!(*r1, *r2);
+    
+    // 判断两个内存地址的字符串是否相等
+    assert_eq!(get_addr(r1),get_addr(r2));
+}
+
+// 获取传入引用的内存地址的字符串形式
+fn get_addr(r: &char) -> String {
+    format!("{:p}", r)
+}
+```
+
+### 借用规则
+🌟
+```rust,editable
+
+// 移除代码某个部分，让它工作
+// 你不能移除整行的代码！
+fn main() {
+    let mut s = String::from("hello");
+
+    let r1 = &mut s;
+    let r2 = &mut s;
+
+    println!("{}, {}", r1, r2);
+}
+```
+
+#### 可变性
+🌟 错误: 从可不用对象借用可用
+```rust,editable
+
+fn main() {
+    // 通过修改下面一行代码来修复错误
+    let  s = String::from("hello, ");
+
+    borrow_object(&mut s)
+}
+
+fn borrow_object(s: &mut String) {}
+```
+
+🌟🌟 Ok: 从可变对象借用不可变
+```rust,editable
+
+// 下面的代码没有任何错误
+fn main() {
+    let mut s = String::from("hello, ");
+
+    borrow_object(&s);
+    
+    s.push_str("world");
+}
+
+fn borrow_object(s: &String) {}
+```
+
+### NLL
+🌟🌟
+```rust,editable
+
+// 注释掉一行代码让它工作
+fn main() {
+    let mut s = String::from("hello, ");
+
+    let r1 = &mut s;
+    r1.push_str("world");
+    let r2 = &mut s;
+    r2.push_str("!");
+    
+    println!("{}",r1);
+}
+```
+
+🌟🌟🌟
+```rust,editable
+
+fn main() {
+    let mut s = String::from("hello, ");
+
+    let r1 = &mut s;
+    let r2 = &mut s;
+
+    // 在下面增加一行代码人为制造编译错误：cannot borrow `s` as mutable more than once at a time
+    // 你不能同时使用 r1 和 r2
+}
+```
\ No newline at end of file