What happens if you "my" the $str inside the foreach of the first sub listing?
Joe Frazier, Jr. Senior Support Engineer Peopleclick Service Support Tel: +1-800-841-2365 E-Mail: [EMAIL PROTECTED] > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Glenn Linderman > Sent: Tuesday, July 27, 2004 2:36 AM > To: GUI > Subject: [perl-win32-gui-users] exception in Perl's C code... > "fixed" by reworking the Perl source. But why? > > So, I find this to be an interesting problem. Probably my > "fix" just hides the problem, rather than fixing it. It > smells of an unitialized variable "somewhere". > > I have this Perl program that works consistently correctly on > Win2K. On WinXP, it fails pretty regularly but not always, > on certain operations. > > This Perl program uses Win32::GUI, and contains a combobox > widget. On occasion, and as part of the operation that makes > the program fail with an access violation, it needs to read > the contents of the combobox. It uses the following > subroutine to do so. > > After figuring out how to install symbols for Perl, using > MSVC++6.0's debug IDE traceback, I discovered the failure > happens in interpreting this sub, called from DoEvent. The > sub is fairly straightforward, in wanting to copy each entry > from the ComboBox into the key of a hash. > The data are all unique, as the combobox was populated from a > hash initially. The actual failure was in reading some hash > value or property (if I can guess at the Perl internal symbol > names reasonably). > > The first subroutine below is how it was, when it worked on > Win2K and failed on WinXP. The second subroutine succeeded 3 > timse in a row on WinXP. > > Clearly my modified version and the original version do the > same job, but the modified version does it "slower" by using > an intermediate array. (A slow algorithm is faster than a > broken algorithm.) However, I see no reason why this should > "fix" a crash, nor why the crash should be there in the first place. > > > # bad > ##################################### > sub read_lb # version 2002/02/23 > { my ( $lb ) = @_; > my ( %hash, $count, $ix, $str ); > $count = $lb->Count () - 1; > foreach $ix ( 0 .. $count ) > { $str = $lb->GetString ( $ix ); > $hash{ $str } = 1; > } > return \%hash; > } > ##################################### > > > # good > ##################################### > sub read_lb # version 2002/07/26 > { my ( $lb ) = @_; > my ( %hash, $count, $ix, @str ); > $count = $lb->Count () - 1; > foreach $ix ( 0 .. $count ) > { push @str, $lb->GetString ( $ix ); > } > foreach my $str ( @str ) > { $hash{ $str } = 1; > } > return \%hash; > } > ##################################### > > -- > Glenn -- http://nevcal.com/ > =========================== > The best part about procrastination is that you are never > bored, because you have all kinds of things that you should be doing. > > > > ------------------------------------------------------- > This SF.Net email is sponsored by BEA Weblogic Workshop > FREE Java Enterprise J2EE developer tools! > Get your free copy of BEA WebLogic Workshop 8.1 today. > http://ads.osdn.com/?ad_id=4721&alloc_id=10040&op=click > _______________________________________________ > Perl-Win32-GUI-Users mailing list > Perl-Win32-GUI-Users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/perl-win32-gui-users > > >
