No debate, std::endl can be a disaster on some platforms due to flushing crap all the time.
this post was submitted on 05 Apr 2025
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It's a very C++ thing that the language developers saw the clusterfuck that is stream flushing on the kernel and decided that the right course of action was to create another fucking layer of hidden inconsistent flushing.
I hear C++ was greatly inspired by the fifth circle of hell.
programmers manage to do stupid shit in every language. i was wondering if there was a way to stop them, and golang comes close but maybe proves it can't be done. idk!
Just because the box says something is flushable doesn't mean you should flush it.
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printf is superior and more concise, and snprintf is practically the only C string manipulation function that is not painful to use.
Try to print a 32-bit unsigned int as hexadecimal number of exactly 8 digits, using cout. You can do std::hex and std::setw(8) and std::setfill('0') and don't forget to use std::dec afterwards, or you can just, you know, printf("%08x") like a sane person.
Just don't forget to use -Werror=format but that is the default option on many compilers today.
C++23 now includes std::print which is exactly like printf but better, so the whole argument is over.
I went digging in cppref at the format library bc I thought c++20 or c++23 added something cool.
Found std::print and was about to reply to this comment to share it bc I thought it was interesting. Then I read the last sentence.
Darn you and your predicting my every move /j
I am very sorry to remind everyone about the existence of Visual Basic, but it has:
- VbCrLf
- VbNewLine
- ControlChars.CrLf
- ControlChars.NewLine
- Environment.NewLine
- Chr(13) & Chr(10)
And I know what you're asking: Yes, of course all of them have subtly different behavior, and some of them only work in VB.NET and not in classic VB or VBA.
The only thing you can rely on is that "\r\n" doesn't work.
Apology not accepted, fuck you for reminding me!
great reminder to avoid microsoft products as much as i can
Simple. \n when you just want a newline.
endl when you need to flush at the moment.
Useful in case you are printing a debug output right before some function that might do bed stuff to buffers.
Edit: I wrote println instead of endl somehow. Guess I need more downtime
I only program in C. I was under the assumption that \n also flushes
It depends on whether you are printing to a terminal or to a file (and yes the terminal is also a file), and even then you can control the flushing behaviour using something like unbuffer
I remember having to fflush a couple of times.
I prefer \n for 0.001% better performance
std::cout << "\nwhy not both" << std::endl;
fprintf(stdout, "%c", '\012');
print('string\n', end='')
I just learned that in Python, it's fucking terrible. Python is a fucking mess and my next script will be in a different language.
python is a bad joke that never ends
Perhaps TS is not a terrible language for shell scripts after all
Never tried it, but I will probably be more at home than python.
As a python lover, I have to ask, what don't you like about it and what languages do you generally prefer?
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In PHP it exists as well. I try to use PHP_EOL but when I'm lazy I simply do "\n".
For me the answer is “Building backend applications with it instead of CLI applications, like Lerdorf intended.”
But also "\n" because it's easier and PHP_EOL is just an alias for "\n"; it's not even platform-dependent.
PHP_EOL depends on your host system, it's \r\n on Windows.
I don't really want to use what Lerdorf intended, PHP <= 4 was horrible, 5.x was mainly getting slowly rid of nonsense and with 7.x PHP started its slow path of redemption and entered its modern era.
While Lerdorf's vision was great at that time for its intended use case, I wouldn't want to build anything serious in it.
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Wasn't this {fmt} library merged into STL now? Does this solve this issue?
Anyways, there was also a constant that is the OS line ending without a flush, right?
C++ style text streams are bad and a dead-end design and '\n'.
Maybe c# has similar. There's \r\n or \n like c++ and Environment.NewLine.
Probably it's similar in that Environment.NewLine takes into account the operating system in use and I wonder if endl in c++ does the same thing?
C# also has verbatim strings, in which you can just put a literal newline.
string foo = @"This string
has a line break!";
Just puts(“I’m a teapot”); :)
Kinda in Java, you can call System.out.println or you can call System.out.print and explicitly write the newline.
I haven't looked at the code but I always assumed that println was a call to print with a new line added to the original input.
Something like this:
void print(String text) { ... }
void println(String text) { this.print(text + '\n'); }
That is pretty much what it does except it doesn't hardcode \n but instead uses the proper line ending for the platform it's running on.
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If endl is a function call and/or macro that magically knows the right line ending for whatever ultimately stores or reads the output stream, then, ugly though it is, endl is the right thing to use.
If a language or compiler automatically "do(es) the right thing" with \n as well, then check your local style guide. Is this your code? Do what you will. Is this for your company? Better to check what's acceptable.
If you want to guarantee a Unix line ending use \012 instead. Or \cJ if your language is sufficiently warped.
It's a "stream manipulator" function that not only generates a new line, it also flushes the stream.
Ah don't worry, if you do fopen(file, "w") on Windows and forget to use "wb" flag, it will automatically replace all your \n with \r\n when you do fwrite, then you will try to debug for half a day your corrupted jpeg file, which totally never happened to me because I'm an experienced C++ developer who can never make such a novice mistake.
As long as it doesn't end in ;
\n is fun until you’re an a system that needs an additional \r
Unix needed only \n because it had complex drivers that could replace \n with whatever sequence of special characters the printer needed. Also, while carriage return is useful, they saw little use for line feed
On dos (which was intended for less powerful hardware than unix) you had to actually use the correct sequence which often but not always was \r\n (because teleprinters used that and because it's the "most correct" one).
Now that teleprinters don't exist, and complex drivers are not an issue for windows, and everyone prefers to have a single \n, windows still uses \r\n, for backward compatibility.
Bedeviled NXP/ARM SDK stdlib. Hate it, we need \n\r there. Why????!?!?! What a PITA.
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