[ILUG] Silly perl question

[Cian Brennan]

That's because they weren't defined in myswap. You're confusing local with my.

variables created with local are local to the sub/package/module/loop/whatever
esle they're created in. You seem to want to declare $y and $x as local within
myswap()
On Thu, Aug 28, 2008 at 11:14:00AM +0100, Braun Brelin wrote:
> The other odd thing is that the perl I'm using doesn't seem to have local
> vs. global variable scoping...
> 
> 
> --   Perl script --
> #!/usr/bin/perl
> use strict;
> 
> my $x=1;
> my $y=10;
> 
> myswap();
> 
> sub myswap {
>     $y = $x;
> }
> 
> print "y = ",$y,"\n";
> 
> -------------------------------------------------------------------------
> 
> Not only doesn't it complain about x and y not being
> defined in myswap, it goes ahead and changes the
> x and y defined outside the myswap function...
> 
> Braun
> 
> 
> 
> On Thu, Aug 28, 2008 at 11:10 AM, Braun Brelin <bbrelin at gmail.com> wrote:
> 
> > Doesn't use strict require that all variables be declared before they are
> > used regardless of whether they're global or local?
> >
> > Braun
> >
> >
> >
> > On Thu, Aug 28, 2008 at 11:06 AM, Jimmy O'Regan <joregan at gmail.com> wrote:
> >
> >> 2008/8/28 Braun Brelin <bbrelin at gmail.com>:
> >> > Hello all,
> >> >
> >> > I have a silly Perl question.  I'm running an Ubuntu Linux system
> >> (8.04),
> >> > with Perl 5.8.8.
> >> >
> >> > However, the 'use strict' pragma seems not to be working.  I.e. I have
> >> the
> >> > following
> >> > Perl script:
> >> >
> >> > #!/usr/bin/perl
> >> >
> >> > use strict;
> >> >
> >> > $a=10;
> >> >
> >> > print "a = ",$a,"\n";
> >> >
> >> > This should fail miserably with an error about not having $a declared,
> >> but,
> >> > unfortunately, it doesn't.  It just prints '10'.
> >> >
> >> > This isn't my normal machine so I'm not sure how Perl was built,
> >> although I
> >> > suspect
> >> > that it isn't anything more than a standard install.  perl -V didn't
> >> really
> >> > give me any clues.  Anything stupidly obvious that I'm missing?
> >>
> >> You've declared it as a global variable; 'my' is used to declare a
> >> local variable
> >>
> >> #!/usr/bin/perl
> >>
> >> use warnings;
> >> use strict;
> >>
> >> foo();
> >>
> >> sub foo
> >> {
> >>        $a=10;
> >>
> >>        print "a = ",$a,"\n";
> >> }
> >> print $a;
> >>
> >> gives:
> >> a = 10
> >> 10
> >> --
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> >>
> >
> >
> -- 
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