Re: Timerproc exception

From:

"Doug Harrison [MVP]" <dsh@mvps.org>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 06 Oct 2007 11:39:37 -0500

Message-ID:

<t1efg3lro71hfmcdverlghcsto7cet3l97@4ax.com>

On Fri, 5 Oct 2007 23:18:01 -0700, Geoff Cohen
<GeoffCohen@discussions.microsoft.com> wrote:

Thanks. I realise I'm going to have to read up a lot on exceptions if I want
to know what's really going on. For the record, here's the essence of what
happened:
(using VC++ 6 with default setting for /EH)

void CALLBACK timerproc(..)
{
try {
   ...
   FILE *fp;
   ...
   fgets (..., fp); // sometimes fp is NULL!
  ...
}
catch (CException *e) {..}
catch (std::exception &e) {..}
..
} // end of timerproc
A program log tells me that 'fgets' is entered, but does not return by the
usual route, nor is an exception caught; but the timer proc is re-entered
normally when the timer next fires.
At least my bug ultimately has a trivial solution, making sure fp != NULL,
but it was hellish to find!

I can't comment on the omitted code, but the code you've shown doesn't
throw C++ exceptions, so it's not surprising that neither of the catch
handlers is entered. I suspect the answer is related to what I posted in my
last message.

--
Doug Harrison
Visual C++ MVP