I have recently read an article which stated that using \n is preferable to using std::endl because endl also flushes the stream.
But when I looked for a bit more information on the topic I found a site which stated:
If you are in a situation where you have to avoid buffering, you can use std::endl instead of ‘\n’
Now here comes my question: In which situation is it preferable not to write to the buffer? Because I only saw advantages of that technique. Isn't it also safer to write to the buffer? Because it is smaller than a hard drive it will get overwritten faster than data that is stored on the HD (I am not sure if this is true).
When buffering occurs you will have no guarantees that the data is immediately received before a flush occurs. Under particular circumstances you might experience wrong output ordering and/or loss of information/debug data, e.g.
int main() {
std::cout << "This text is quite nice and might as well be buffered";
raise(SIGSEGV); // Oh dear.. segmentation violation
std::cout << std::endl;
}
Output:
bash: line 7: 22235 Segmentation fault (core dumped) ./a.out
the above will not print any text since the buffering prevented the right output to be displayed.
Now if you simply add a flushing std::endl at the end of the buffer this is what you get
int main() {
std::cout << "This text is quite nice and might as well be buffered" << std::endl;
raise(SIGSEGV); // Oh dear.. segmentation violation
std::cout << std::endl;
}
Output:
This text is quite nice and might as well be buffered
bash: line 7: 22444 Segmentation fault (core dumped) ./a.out
This time the output is visible before the program termination.
Implications of this fact are manifold. Purely speculative: if the data were related to a server log, your app could have crashed before the actual logging.