book: fix incorrect return value description of std::weak_ptr expired (#144)

* Fix error

资源尚存在时,`std::weak_ptr` 的 `expired()` 方法返回 `false`, 否则返回 `true`。

* book: fix error

Fix error, while the resource of `std::shared_ptr` exists, `std::weak_ptr`'s `expired()` method returns `false`, otherwise it returns `true`.
This commit is contained in:
Tengfei Niu
2020-11-17 15:34:05 +08:00
committed by GitHub
parent 56de7fa327
commit 1e78a01ac0
2 changed files with 3 additions and 3 deletions

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@@ -187,7 +187,7 @@ The solution to this problem is to use the weak reference pointer `std::weak_ptr
In the above figure, only B is left in the last step, and B does not have any smart pointers to reference it, so this memory resource will also be released.
`std::weak_ptr` has no `*` operator and `->` operator, so it can't operate on resources. Its only function is to check if `std::shared_ptr` exists, its `expired() The ` method can return `true` when the resource is not released, otherwise it returns `false`.
`std::weak_ptr` has no `*` operator and `->` operator, so it can't operate on resources. Its only function is to check if `std::shared_ptr` exists, its `expired()` method can return `false` when the resource is not released, otherwise it returns `true`.
## Conclusion
@@ -201,4 +201,4 @@ The technology of smart pointers is not novel. It is a common technology in many
## 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).

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@@ -175,7 +175,7 @@ int main() {
在上图中,最后一步只剩下 B而 B 并没有任何智能指针引用它,因此这块内存资源也会被释放。
`std::weak_ptr` 没有 `*` 运算符和 `->` 运算符,所以不能够对资源进行操作,它的唯一作用就是用于检查 `std::shared_ptr` 是否存在,其 `expired()` 方法能在资源未被释放时,会返回 `true`,否则返回 `false`
`std::weak_ptr` 没有 `*` 运算符和 `->` 运算符,所以不能够对资源进行操作,它的唯一作用就是用于检查 `std::shared_ptr` 是否存在,其 `expired()` 方法能在资源未被释放时,会返回 `false`,否则返回 `true`
## 总结