What's the difference between std::endl and '\n'

问题

I've read the difference between std::endl and '\n' is that std::endl flushes the buffer and '\n' doesn't. However, as far as I know stdout on linux is line-buffered anyway, so does it mean that std::cout << ... << std::endl is the same as std::cout << ... << '\n'?

回答1:

std::ostream os;

os << std::endl; // more concise

os << '\n' << std::flush; // more explicit about flushing

Those two lines have the exact same effect.

The manual flushing is often a waste of time:

• If the output stream is line-buffered, which should be the case for std::cout if it connects to an interactive terminal and the implementation can detect that, then printing \n already flushes.

• If the output stream is paired with an input stream you read from directly afterwards (std::cout and std::cin are paired), then reading already flushes.

• If you nobody waits for the data to arrive at its destination, flushing is again just going to waste.

回答2:

This std::cout << ... << std::endl and this std::cout << ... << '\n' are not exactly the same. In the last one, the newline \n is streamed to the output. In most cases this will be interpreted by a console as a newline. But std::endl means (as you already mentioned) exactly flush and newline in the output console.

Assume you would write this in a document. In Linux the \n is sufficient. But Windows expects \r\n. So the new lines will not occur using \n and e.g. Notepad++ in Windows.

来源：https://stackoverflow.com/questions/64253865/whats-the-difference-between-stdendl-and-n