book: fix incorrect string literal (changkun#102) and a typo (changkun#103)

cathaysia · web-flow · commit 3abc907bb4da · 2020-06-03T08:19:41.000+02:00
diff --git 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
 
-<a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-nd/4.0/88x31.png" /></a><br />This work was written by [Ou Changkun](https://changkun.de) and licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License</a>. The code of this repository is open sourced under the [MIT license](../../LICENSE).
+<a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-nd/4.0/88x31.png" /></a><br />This work was written by [Ou Changkun](https://changkun.de) and licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License</a>. 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
@@ -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<int> 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，
