this post was submitted on 05 Apr 2025
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[–] [email protected] 45 points 1 week ago* (last edited 1 week ago) (1 children)

If I'm writing C++, I'm usually optimizing for portability over performance, in which case I would prefer std::endl as it would yield the best results regardless of platform; it also keeps the end-of-line character out of other strings, making code just a little cleaner.

\n is for when I'm done pretending that anything that isn't Unix-like is OK, or I'm counting the cycles of every branch instruction.

[–] [email protected] 32 points 1 week ago (2 children)

std::endl provides zero portability benefits. C++ does have a portable newline abstraction, but it is called \n, not endl.

[–] Albbi 50 points 1 week ago

Thank you two for demonstrating the image in the post so well.

[–] [email protected] 8 points 1 week ago (1 children)

No, there's no guarantee that in every context \n is translated portably.

[–] [email protected] 15 points 1 week ago (2 children)

The same is true of std::endl. std::endl is simply defined as << '\n' << std::flush; nothing more, nothing less. In all cases where endl gives you a "properly translated" newline, so does \n.

[–] [email protected] 6 points 1 week ago (1 children)

Ahhh, I see. Looks like the magic happens somewhere further down in iostream.

[–] [email protected] 3 points 1 week ago

It's controlled by whether the stream's opened in text mode or binary mode. On Unix, they're the same, but on Windows, text mode has line ending conversion.

[–] [email protected] 2 points 1 week ago

Yeah it's an artificial dichotomy based on a popular misconception of what std::endl is and how \n is interpreted.

Ultimately it does not ask about line endings, but about flushing, which is a completely orthogonal question.

[–] [email protected] 21 points 1 week ago (2 children)

They aren't the same thing so the comparison is weird.

endl has a flush which is important when doing something like embedded work or RTOS development. If i was doing multiple lines they all were \n until the last line when i actually want to push the buffer.

Obviously depending on the tuning of the compiler's optimization multiple flushes could be reduced but the goal should always be to write as optimal as possible.

[–] [email protected] 3 points 1 week ago

but the goal should always be to write as optimal as possible.

Within reason.

Over optimization is a curse on getting done.

[–] [email protected] 3 points 1 week ago (2 children)

Who in the hell is using iostreams in an RTOS

[–] [email protected] 2 points 1 week ago

Several. Probably dozens

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[–] [email protected] 19 points 1 week ago

\n, because I ordered a newline, not a flush.

[–] [email protected] 17 points 1 week ago (5 children)
[–] [email protected] 40 points 1 week ago (1 children)

std::endl is used in output streams in C++ to end the line, using the os specific line termination sequence, and flush the buffer.

The later one is a performance issue in many cases, why the use of "\n" is considered preferred

[–] [email protected] 2 points 1 week ago (2 children)

Don’t most terminals flush the buffer on newline anyway?

[–] [email protected] 7 points 1 week ago

It is the stream itself that is buffered, so the terminal does not handle the contents until the stream is flushed.

[–] [email protected] 2 points 1 week ago

Maybe, but there is the internal buffer. Also, most I/O happens in files not consoles

[–] hellfire103 10 points 1 week ago* (last edited 1 week ago) (5 children)

Instead of this:

cout << "Hello world.\n";

You can do this:

cout << "Hello world." << endl;
[–] [email protected] 5 points 1 week ago

The fact that you used the namespace for cout but not for endl inordinately bothers me

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[–] [email protected] 7 points 1 week ago (2 children)
[–] [email protected] 11 points 1 week ago (2 children)

Boy am I glad I don’t do C++ anymore. That string handling with the overloaded bitshift operator was wild.

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[–] [email protected] 2 points 1 week ago

Alternatively:

https://en.cppreference.com/w/cpp/io/manip/endl

p.s. The site isn't entirely mobile friendly

(I'm a cppref lover tbh)

[–] [email protected] 3 points 1 week ago

From memory it's a way to declare a line ending after your string.

[–] [email protected] 2 points 1 week ago

God bless your soul.

[–] [email protected] 15 points 1 week ago

#define endl "\n"

[–] [email protected] 11 points 1 week ago (1 children)
[–] [email protected] 8 points 1 week ago
/* I'm new to this language so just imagine there is a new line here when it prints: */
[–] besselj 10 points 1 week ago (2 children)
[–] [email protected] 20 points 1 week ago (1 children)
[–] [email protected] 3 points 1 week ago

Yeah \r gang4lyfe

[–] [email protected] 2 points 1 week ago (1 children)

Are you a modem by any chance?

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[–] [email protected] 9 points 1 week ago

os.linesep

Lol jk none of my stuff runs on Windows anyway

[–] [email protected] 8 points 1 week ago (1 children)
[–] [email protected] 2 points 1 week ago (1 children)

I like that you added the absolute namespace identifier or whatever its called

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[–] [email protected] 5 points 1 week ago
[–] [email protected] 5 points 1 week ago (2 children)

Environment.NewLine might exist in C#

[–] [email protected] 2 points 1 week ago

It might do. I encountered it last week as I needed it for a powershell script. So it exists in that at least

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[–] [email protected] 5 points 1 week ago
[–] [email protected] 4 points 1 week ago

Rebel side \0

[–] [email protected] 4 points 1 week ago

Well, Java has System.lineSeparator so, maybe no?

[–] [email protected] 3 points 1 week ago
[–] [email protected] 2 points 1 week ago

Endl is faster to type

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