c++ "cout << number" results with printing "number%" to the screen

Question

I have a strange problem, simple program, f.e.

main()
{
    int i=1;
    std::cout << i;
}

Results with

1%

on screen. I can't get rid of that "%". Does anyone know what is going on? I am using g++ (GCC) 4.8.0 20130502 on Arch Linux.

what happens if you add `<<"\n";` to the second line? is "%" a part of your prompt? — Begelfor, May 19 '13 at 11:04

score 5 · Accepted Answer · edited May 19 '13 at 11:04

5

The '%' is not from the program - It is from the shell that you are running it from.

Try

std::cout << i << std::endl;

edited May 19 '13 at 11:04

user123

answered May 19 '13 at 11:04

Ed Heal

(Removed the `;` in the middle of the statement) – user123 May 19 '13 at 11:04
@WayneUroda - just curious - why a +1 for `endl`? – user93353 May 19 '13 at 11:14
@user93353 - People tend to forget! – Ed Heal May 19 '13 at 11:15
We all have a "senior" moment once in a while! – Ed Heal May 19 '13 at 11:25
@user93353 I thought I knew (I thought it was "more correct" C++, also I thought it was more platform aware [linux uses \n for line endings, windows uses \r\n, some older crazy systems used \r...]) but after looking into it now, I'm not so sure. In this case it flushes the `cout` stream immediately whereas `'\n'` or `"\n"` doesn't. See this question: http://stackoverflow.com/questions/213907/c-stdendl-vs-n – Wayne Uroda May 20 '13 at 01:21
@WayneUroda - I know - that's why I asked. endl isn't more correct or more platform aware. – user93353 May 20 '13 at 02:47
@user93353 well as they say, 'you learn something new every day", so thanks for pointing that out. Still, I think I would prefer endl in my own code, just a style choice more than anything (unless there was some performance critical aspect). – Wayne Uroda May 20 '13 at 03:00

score 2 · Answer 2 · answered May 19 '13 at 11:03

2

Is the % your shell prompt?

If so, change your cout line to

std::cout << i <<'\n';

Run echo $PS1 in your shell to see what's your prompt.

Your original program prints 1 & then the shell prints the % prompt.

answered May 19 '13 at 11:03

user93353

2 Answers2