修复 bool 相关的示例代码#80
Open
frederick-vs-ja wants to merge 1 commit into
Open
Conversation
archibate
reviewed
Feb 26, 2025
|
|
||
| ```cpp | ||
| char c = 0; | ||
| bool b = *(bool *)&c; // 可以，b = false |
Contributor
Author
There was a problem hiding this comment.
原来的写法导致 UB。你觉得应该保留吗？
Contributor
There was a problem hiding this comment.
你是说 bool b = *(bool *)&c; 是UB？为什么？据我所知char和任意类型的“类型双关”都是允许的，bool和char当然也是可以“类型双关”的。
Contributor
Author
There was a problem hiding this comment.
你是说
bool b = *(bool *)&c;是UB？为什么？据我所知char和任意类型的“类型双关”都是允许的，bool和char当然也是可以“类型双关”的。
这里的类型双关是单向的。只能通过 char 泛左值访问 bool 对象，但不能反过来。是否有什么资料导致你认为类型双关是双向的呢？
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #74.
严格来说标准并未要求
sizeof(bool) == 1，并且标准允许字节有更多的位。更正后的写法只是适用于绝大多数平台。