Handle Ctrl-C on Windows

cztmonk has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,I have the following code. I want to handle Ctrl-C when waiting for $choice

# Handle Ctrl-C
$SIG{INT} = \&ctrlc;

use autodie;
use Modern::Perl;
use Storable qw {store retrieve};

my $dbfile = 'sbs.db';
my %person = %{ retrieve($dbfile) };

while() {
  print "\n(C)reate,(L)ist,(N)ew,(M)odify,(R)emove,(Q)uit? ";
  chomp(my $choice = <>);
  $choice = lc $choice;
  #
  # Some code here
  # 
  
}
exit;
  
sub ctrlc {
  store \%person,$dbfile;
  print "You used Ctrl-C!";
  exit 1;
}
[download]

When I press Ctrl-C, I get the following messages :

(C)reate,(L)ist,(N)ew,(M)odify,(R)emove,(Q)uit? Use of uninitialized v
+alue $choice in chomp at J:\ps
\monks.pl line 13.
Use of uninitialized value $choice in lc at J:\ps\monks.pl line 14.
You used Ctrl-C!
[download]

How can I avoid the error messages? And have a clean exit?

Comment on Handle Ctrl-C on Windows Select or Download Code

Replies are listed 'Best First'.
Re: Handle Ctrl-C on Windows by marto (Cardinal) on Aug 28, 2012 at 10:32 UTC
See ctrl + c on Win32 (signal handling), Term::ReadKey or use Super Search/your search engine of choice to find similar posts.	[reply]
Re: Handle Ctrl-C on Windows by jethro (Monsignor) on Aug 28, 2012 at 09:49 UTC
I don't get that warning on linux, so can't test, but the problem seems to be that the chomp is executed even after you pressed ctrl-C. Did you try to move the chomp on a line by itself or add a noop inbetween so that there is another statement to break on? `my $choice = <>; chomp($choice); #or even my $choice = <>; $choice=$choice; chomp($choice);` [download]	[reply] [d/l]
Re^2: Handle Ctrl-C on Windows by cztmonk (Monk) on Aug 28, 2012 at 10:14 UTC
Thanks for your advice.Tried both, but the same results :(	[reply] [d/l]
Re: Handle Ctrl-C on Windows by philiprbrenan (Monk) on Aug 28, 2012 at 11:49 UTC
May I suggest that you call Storable::store() in your: `# some code here` [download] processing on a regular basis? The problem with calling store() at random points is that the data structure you want to save may be in an inconsistent state. Storable::store is very efficient and so it is not a problem to call it frequently whenever you have made a consistent set of modifications to your data, perhaps, for example, at the end of your while loop. This would eliminate the need to catch the Ctrl-C in your code and so make your script simpler and more reliable.	[reply] [d/l]
Re^2: Handle Ctrl-C on Windows by cztmonk (Monk) on Aug 29, 2012 at 06:54 UTC
I have decided to do just that. I thank you for the reply.	[reply] [d/l]