C++是什么？ iostream endl 惨败？
当我正在听 Andrei Alexandrescu 关于 D 编程的 Google 演讲时，他放弃了关于“endl”惨败的一则短文。我只是认为 endl 是表示行结束和刷新流缓冲区的首选方式。为什么它被认为是一场惨败？我不应该在我的代码中使用它吗？
I was listening to a google talk by Andrei Alexandrescu on the D programming language when he threw out a one liner about the "endl" fiasco. I just thought endl was the preferred way to signify the end of a line and flush the buffer for a stream. Why is it considered a fiasco? Should I not be using it in my code?
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（2）
（我认为）他只是意味着许多，尤其是新的 C++ 程序员盲目地使用
std::endl而不是'\n'来换行，不必要地频繁刷新，并可能使他们的程序的性能很糟糕。也就是说，大多数人都被告知
std::endl是在流中插入换行符的规范方法，尽管它很少有必要或适当冲洗。有些人认为（*咳嗽*）
std::endl甚至不应该出现在标准中，因为它很少适用，并且不会节省显着的打字量超过'\n' <<无论如何，std::flush。TL;DR(s):
std::endl除了通常更差性能之外什么也没有给你带来通常需要更多的打字。(I assume) He just means that many, especially new, C++ programmers use
std::endlblindly instead of'\n'for newline, flushing unnecessarily frequently and potentially making the performance of their program abysmal.I.e., most people are taught that
std::endlis the canonical way to insert a newline into a stream even though it is very rarely necessary or appropriate to flush it.It is some people's opinion (*cough*) that
std::endlshouldn't even be in the standard, as it is so rarely appropriate and not a significant typing savings over'\n' << std::flushanyway.TL;DR(s):
std::endlbuys you nothing except usually worse performance and usually more typing.为了补充已经很好的答案，这个问题可以扩展到“iostream”惨败。
一般来说，使用 iostream 会带来性能损失，因为它被设计为与 stdio 流（
printf和scanf）同步，以便您可以混合使用 isotream 和 stdio如果需要的话。如果您只打算使用一个，则可以通过调用
std::ios::sync_with_stdio(false)来获得性能优势。然而，我相信，未同步的流不再是线程安全的......请参阅此处和此处以及文档这里。
To add to the already great answer, this issue can be extended to the 'iostream' fiasco.
Using iostream in general has a performance penalty because it is designed to be synced up with the stdio streams (
printfandscanf) so that you can use a mix of isotream and stdio if so desired.If you are only going to be using one you can get a performance benefit by calling
std::ios::sync_with_stdio(false). I believe, however, the unsynced streams are no longer thread safe...See more here and here as well as documentation here .