我可以停止 std::cout 对“\n”的刷新吗？
根据 这篇文章 std::cout 将自动刷新\n 当它附加到交互式设备（例如终端窗口）时。 否则（例如，当通过管道传输到文件时）它将完全缓冲，并且仅在 .flush() 或 std::endl 上刷新。
有没有办法在 Microsoft Visual C++ 中覆盖此行为，以便我可以选择是否需要完全缓冲模式或行缓冲模式？
According to to this post std::cout will automatically flush on \n when it is attached to an interactive device (e.g. a terminal window). Otherwise (e.g. when being piped to a file) it will act fully buffered and will only flush on .flush() or std::endl.
Is there a way to override this behaviour in Microsoft Visual C++ so that I can select whether I want fully buffered or line buffered mode?
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与 anon（2009 年 4 月 28 日）的回答相反，此行为与操作系统或“控制台软件”无关。
C++ 的
std::cout的使用与printf/puts的使用混合在一起。 为了实现这一点，std::cout的streambuf是在 C 的stdout流之上实现的。 当标准输出连接到终端设备时，实际上是 C 的stdout进行行缓冲。您可以调用
std::ios_base::sync_with_stdio(false)（在您的程序使用任何 C++ 的标准 I/O 流之前）告诉 C++ 流库直接与底层文件描述符通信，而不是分层在 C 的流库之上。 这完全避免了 C 的 stdout 流并加速了 C++ 的 I/O 流，但代价是两个库不再能够很好地混合。另一种方法是通过调用 无条件地将
stdout设置为完全缓冲std::setvbuf(stdout, nullptr, _IOFBF, BUFSIZ)。 然后，即使std::cout仍然通过stdout写入，您也不会在每个换行符之后刷新stdout。Contrary to anon's (Apr 28 '09) answer, this behavior has nothing to do with the operating system or "console software."
C++'s
<iostream>streams are designed to be interoperable with C's<stdio.h>streams. The goal is to allow uses ofstd::coutto be intermixed with uses ofprintf/puts. To achieve this,std::cout'sstreambufis implemented atop C'sstdoutstream. It is actually C'sstdoutthat is line-buffered when the standard output is attached to a terminal device.You can call
std::ios_base::sync_with_stdio(false)(before your program uses any of C++'s standard I/O streams) to tell the C++ streams library to communicate directly with the underlying file descriptors rather than layering atop C's streams library. This avoids C'sstdoutstream entirely and speeds up C++'s I/O streams at the cost of the two libraries no longer mixing well.An alternative is to unconditionally set
stdoutto fully buffered by callingstd::setvbuf(stdout, nullptr, _IOFBF, BUFSIZ). Then, even thoughstd::coutis still writing throughstdout, you will not havestdoutflushing after every newline.这不是 C++ 的问题（没有刷新任何内容的语言要求），而是操作系统和/或控制台软件的问题。 如果控制台在看到换行符时想要刷新其缓冲区，那么它可以，而且我猜大多数人都会这样做。 请注意，区分 C++ 运行时的缓冲区（在某种程度上可以由 C++ 代码控制）和控制台应用程序的缓冲区（它无法控制）非常重要。
仅供参考，标准 iostream 库中有一个名为 unitbuf 的标志，如果设置该标志，则会在每次输出操作后刷新缓冲区。 例如，它是为 std::cerr 流设置的。 然而，这与 '\n' 字符无关，因为您可以在单个操作中输出多个 '\n' 。
This is not an issue with C++ (there is no language requirement that \n flushes anything) but with your operating system and/or console software. If the console wants to flush its buffer when it sees a newline, then it can, and I would guess that most do so. Note that it is important to differentiate between the C++ runtime's buffers (which can be to some extent controlled from your C++ code) and the buffers of the console application (over which it has no control).
FYI, there is a flag in the standard iostream library called unitbuf which if set causes the buffers to be flushed after each output operation. It is set, for example, for the std::cerr stream. This has nothing to do with the '\n' character however, as you can output multiple '\n' s in a single operation.
只要认为合适，实现就可以自由刷新。 是否刷新
\n因供应商而异。我可以看到名为 ios_base& 的东西 nounitbuf(ios_base& str); 来自我的 C++0x 草案。 试一试。 这是标准 C++ 为您提供的唯一东西。
An implementation is free to flush whenever it feels it is appropriate. It varies from vendor to vendor whether they flush on
\nor not.I can see something called
ios_base& nounitbuf(ios_base& str);from my C++0x draft. Give it a shot. This is about the only thing that standard C++ gives you.