Race condition (sort of)? message box verus function return

SDL Development
1

Hi, my message box is appearing before function return before it…

Code:

cout<<“Call_SDL_GetCurrentDisplayMode”<<endl;
call_getCurrentDisplayMode(horizontal, vertical, &dm);
cout<< horizontal << “\t”<< vertical << ‘\n’;

MessageBox(0,"ScreenTest", "Ready?", MB_OK);

Well screentest pops up, and when I press “Ok”, the horizontal and vertical are then printed. I can live with it – jut wanted to know whether this is a permanent condition or whether there wa a workaround.

Thx

2

Try replacing the ‘\n’ with std::endl, or inserting std::flush after the ‘\n’.

-H-----
“After you finish the first 90% of a project, you have to finish the
other 90%.” - Michael Abrash

3

Hi,

Thank you for the solutions, they all worked. Of all the combinations I tried, the one below worked the best:

Code:

std::cout<< horizontal <<"\t"<<std::flush<< vertical << “\t”<<std::flush<<endl;

Generally speaking, why did flushing the stream and combinations, etc., work to speed up the routine?

4

It doesn’t speed anything up. There’s also no race condition, because
these commands are all done on a single thread.

Output streams write to a memory buffer. That memory buffer needs to be
flushed so that it is actually sent to the output device (which could be
anything, not just a simple terminal). C and C++ separate writing and
flushing to give you more control. If you don’t care about that control,
just use std::endl to write a newline and force a flush.

Jonny DOn Mon, Feb 13, 2017 at 12:24 PM, speartip wrote:

Hi,

Thank you for the solutions, they all worked. Of all the combinations I
tried, the one below worked the best:

Code:

std::cout<< horizontal <<"\t"<

Generally speaking, why did flushing the stream and combinations, etc.,
work to speed up the routine?

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5

Hi, points well taken thanks.

What I meant by sped up was that now my cout information was arriving before by message box where it had not before.

6

‘std::cout << std::endl’ is equivalent to ‘std::cout << ‘\n’ <<
std::flush’, so you’re flushing three times here. That’s a bad idea
because flushing slows down the program. I recommend this:

std::cout << horizontal << “\t” << vertical << “\t\n” << std::flush;

Flush exactly once, at the very end of your output, and always use
’std::flush’ instead of ‘std::endl’ because 'std::flush is more explicit
about your intention.On 13.02.2017 18:24, speartip wrote:

std::cout<< horizontal <<"\t"<<std::flush<< vertical << “\t”<<std::flush<<endl;

–
Rainer Deyke - rainerd at eldwood.com

7

Flush exactly once, at the very end of your output, and always use
’std::flush’ instead of ‘std::endl’ because 'std::flush is more explicit
about your intention.

Yes, following that advice, that’s true. Makes more sense when I look at the changes.

That’s a bad idea
because flushing slows down the program.

So what’s the best balance in a speed optimized routine?

8

For optimizing speed, do not print anything at all. :slight_smile:

Jonny DOn Wed, Feb 15, 2017 at 10:00 AM, speartip wrote:

Quote:

Flush exactly once, at the very end of your output, and always use
’std::flush’ instead of ‘std::endl’ because 'std::flush is more explicit
about your intention.

Yes, following that advice, that’s true. Makes more sense when I look at
the changes.

Quote:

That’s a bad idea
because flushing slows down the program.

So what’s the best balance in a speed optimized routine?

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SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

9

[Idea]