tag:help.appveyor.com,2012-11-13:/discussions/questions/1754-synchronisation-of-stdin-stderrAppVeyor: Discussion 2018-10-19T08:17:31Ztag:help.appveyor.com,2012-11-13:Comment/381609202015-10-12T20:33:48Z2015-10-12T20:33:48ZSynchronisation of stdin, stderr<div><p>AppVeyor uses the same pipe for collecting StdOut and StdErr, so
I guess you see the output in the same order it comes to that
pipe.</p></div>Feodor Fitsnertag:help.appveyor.com,2012-11-13:Comment/381609202015-10-12T21:29:01Z2015-10-24T19:28:15ZSynchronisation of stdin, stderr<div><p>I see. However that ordering is not the same as I see in a
CMD<br>
console on Win10.</p>
<p>Usually, one assumes stderr is unbuffered, and stdout is
buffered.<br>
These are C level attributes, the OS may also have buffering<br>
on top of that.</p>
<p>I have switched my program so “write a line to
stdout” writes<br>
and then does a fflush. So I guess what I am seeing<br>
is the stderr is coming out long after stdout. Usually its the<br>
other way around.</p>
<p>In other words the C stderr is in fact buffered.</p>
<p>Interesting. In C++, cout and cerr are <em>required</em> by
default<br>
to be tied (i.e. they have to go to the same ostream).</p>
<p>Ok, so I will have to fflush stderr as well.<br>
Thanks!</p></div>skaller