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Editorial Team
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Asked: 2026-05-13T09:49:20+00:00

Thinking about UNIX, Windows and Mac and an output stream (both binary and text),

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Thinking about UNIX, Windows and Mac and an output stream (both binary and text),

What does std::endl represent, i.e. <CR><LF>, <LF> or <CR>? Or is it always the same no matter what platform/compiler?

The reason I’m asking is that I’m writing a TCP client that talks a protocol that expects each command to end in <CR><LF>. So I’m wondering whether to use std::endl or "\r\n" in my streams.

EDIT: Ok, so one flushes the buffer and another doesn’t. I get that. But if I’m outputting text to a file, is '\n' equal to <LF> or does it convert to <CR><LF> on Windows and <LF> on Unix or not? I don’t see a clear answer yet.

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1 Answer

  1. Editorial Team

    The code:

    stream << std::endl;

// Is equivalent to:

stream << "\n" << std::flush;

    So the question is what is “\n” mapped too.
    On normal streams nothing happens. But for file streams (in text mode) then the “\n” gets mapped to the platfrom end of line sequence. Note: The read converts the platform end of line sequence back to a ‘\n’ when it reads from a file in text mode.

    So if you are using a normal stream nothing happens. If you are using a file stream, just make sure it is opened in binary mode so that no conversion is applied:

    stream << "\r\n"; // <CR><LF>
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