Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit3abc907

Browse files
authored
book: fix incorrect string literal (changkun#102) and a typo (changkun#103)
1 parentf1c1e06 commit3abc907

File tree

2 files changed

+34
-2
lines changed

2 files changed

+34
-2
lines changed

‎book/en-us/03-runtime.md

Lines changed: 17 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -260,6 +260,22 @@ Temporary variables returned by non-references, temporary variables generated
260260
by operation expressions, original literals, and Lambda expressions
261261
are all pure rvalue values.
262262
263+
Note that a string literal became rvalue in a class, and remains an lvalue in other cases (e.g., in a function)：
264+
265+
```cpp
266+
class Foo {
267+
const char*&& right = "this is a rvalue";
268+
public:
269+
void bar() {
270+
right = "still rvalue"; // the string literal is a rvalue
271+
}
272+
};
273+
274+
int main() {
275+
const char* const &left = "this is an lvalue"; // the string literal is an lvalue
276+
}
277+
```
278+
263279
**xvalue, expiring value** is the concept proposed by C++11 to introduce
264280
rvalue references (so in traditional C++, pure rvalue and rvalue are the same concept),
265281
a value that is destroyed but can be moved.
@@ -617,4 +633,4 @@ Lambda expression
617633
618634
## Licenses
619635
620-
<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).
636+
<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).

‎book/zh-cn/03-runtime.md

Lines changed: 17 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -225,6 +225,22 @@ int main() {
225225
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、
226226
原始字面量、Lambda 表达式都属于纯右值。
227227

228+
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：
229+
230+
```cpp
231+
classFoo {
232+
const char*&& right = "this is a rvalue"; // 此处字符串字面量为右值
233+
public:
234+
void bar() {
235+
right = "still rvalue"; // 此处字符串字面量为右值
236+
}
237+
};
238+
239+
int main() {
240+
const char* const &left = "this is an lvalue"; // 此处字符串字面量为左值
241+
}
242+
```
243+
228244
**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，
229245
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。
230246
@@ -252,7 +268,7 @@ std::vector<int> v = foo();
252268

253269
###右值引用和左值引用
254270

255-
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。
271+
要拿到一个将亡值，就需要用到右值引用：`T &&`，其中`T` 是类型。
256272
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。
257273

258274
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，

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp