From 3abc907bb4dab11f0eb7b050e2e15905807d190f Mon Sep 17 00:00:00 2001
From: dragonWater <42114817+cathaysia@users.noreply.github.com>
Date: Wed, 3 Jun 2020 14:19:41 +0800
Subject: [PATCH] book: fix incorrect string literal (#102) and a typo (#103)
---
book/en-us/03-runtime.md | 18 +++++++++++++++++-
book/zh-cn/03-runtime.md | 18 +++++++++++++++++-
2 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/book/en-us/03-runtime.md b/book/en-us/03-runtime.md
index 5ceee68..96e0989 100644
--- a/book/en-us/03-runtime.md
+++ b/book/en-us/03-runtime.md
@@ -260,6 +260,22 @@ Temporary variables returned by non-references, temporary variables generated
by operation expressions, original literals, and Lambda expressions
are all pure rvalue values.
+Note that a string literal became rvalue in a class, and remains an lvalue in other cases (e.g., in a function)：
+
+```cpp
+class Foo {
+ const char*&& right = "this is a rvalue";
+public:
+ void bar() {
+ right = "still rvalue"; // the string literal is a rvalue
+ }
+};
+
+int main() {
+ const char* const &left = "this is an lvalue"; // the string literal is an lvalue
+}
+```
+
**xvalue, expiring value** is the concept proposed by C++11 to introduce
rvalue references (so in traditional C++, pure rvalue and rvalue are the same concept),
a value that is destroyed but can be moved.
@@ -617,4 +633,4 @@ Lambda expression
## Licenses
-
This work was written by [Ou Changkun](https://changkun.de) and licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The code of this repository is open sourced under the [MIT license](../../LICENSE).
\ No newline at end of file
+
This work was written by [Ou Changkun](https://changkun.de) and licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The code of this repository is open sourced under the [MIT license](../../LICENSE).
diff --git a/book/zh-cn/03-runtime.md b/book/zh-cn/03-runtime.md
index 84592d8..023b6ef 100644
--- a/book/zh-cn/03-runtime.md
+++ b/book/zh-cn/03-runtime.md
@@ -225,6 +225,22 @@ int main() {
要么是求值结果相当于字面量或匿名临时对象，例如 `1+2`。非引用返回的临时变量、运算表达式产生的临时变量、
原始字面量、Lambda 表达式都属于纯右值。
+需要注意的是，字符串字面量只有在类中才是右值，当其位于普通函数中是左值。例如：
+
+```cpp
+class Foo {
+ const char*&& right = "this is a rvalue"; // 此处字符串字面量为右值
+public:
+ void bar() {
+ right = "still rvalue"; // 此处字符串字面量为右值
+ }
+};
+
+int main() {
+ const char* const &left = "this is an lvalue"; // 此处字符串字面量为左值
+}
+```
+
**将亡值(xvalue, expiring value)**，是 C++11 为了引入右值引用而提出的概念（因此在传统 C++中，
纯右值和右值是同一个概念），也就是即将被销毁、却能够被移动的值。
@@ -252,7 +268,7 @@ std::vector v = foo();
### 右值引用和左值引用
-需要拿到一个将亡值，就需要用到右值引用的申明：`T &&`，其中 `T` 是类型。
+要拿到一个将亡值，就需要用到右值引用：`T &&`，其中 `T` 是类型。
右值引用的声明让这个临时值的生命周期得以延长、只要变量还活着，那么将亡值将继续存活。
C++11 提供了 `std::move` 这个方法将左值参数无条件的转换为右值，