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

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