seeking clarity regarding std::cout and std::endl

Question

I am trying to get a better understanding of what happens to the buffer when we do not use std::endl after std::cout.

Let us consider the following piece of C++ code -

int main(int argc, char** argv) {

    std::cout << "Hello World!";
    return 0;
}

As per my understanding, std::cout would add the string Hello World! to the buffer. If we do not add std::endl at the end of the code - std::cout << "Hello World!" << std::endl; , should we or should we not expect Hello World! to be printed as output?

score 3 · Accepted Answer · answered May 14 '21 at 14:09

3

Yes, since all streams are flushed at their destructors, and global std::cout object will be destructed upon program exit, the string will be printed.

Note, however, that there will be no new line character in the end of the printed string, so console prompt would look unusual (and ugly) with your regular prompt immediately following Hello World!.

answered May 14 '21 at 14:09

SergeyA

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let's say we add `while(true);` after `std::cout <<"Hello World!";`. Would `Hello World!` be printed on the terminal in this case? – skpro19 May 17 '21 at 17:25
@skpro19 likely no. – SergeyA May 17 '21 at 18:09
But that's not guaranteed. Is it? – skpro19 May 18 '21 at 07:44
1

@skpro19 no, it is not guaranteed, but I would be surprised to see it not happening. – SergeyA May 18 '21 at 12:59

score 0 · Answer 2 · answered May 14 '21 at 14:17

0

To prevent the ugliness SergeyA mentioned but still avoid typing in "<< std::endl" we usually write

std::cout << "Hello World!\n";

the "\n" forcing a new line after the output.

answered May 14 '21 at 14:17

ravenspoint

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seeking clarity regarding std::cout and std::endl

2 Answers2