On Wed, Jun 24, 2009 at 03:25:57PM +0200, Jenda Krynicky wrote:
> From: Roman Makurin <dro...@gmail.com>
> > here is complite perl script which produces such results without
> > any warning:
> >
> > #!/usr/bin/perl
> >
> > use strict;
> > use warnings;
> >
> > use constant {
> > A => 0,
> > B => 1,
> > C => 2 };
> >
> > my @a = (A, B, C);
> > my @b = (1, 2, 3);
> >
> > while(my $i = shift @a) {
> > print $i, $/
> > }
>
> But of course this does not print anything. The shift(@a) returns the
> first element of @a which is zero, assigns that to $i and then checks
> whether it's true. And of course it's not. So it skips the body and
> leaves the loop. Keep in mind that the value of
>
> my $i = shift @a
>
> is NOT a true/false whether there was something shifted from the
> array. It's the value that was removed from the array and assigned to
> the $i. And if that value it false (undef, 0, 0.0, "0", "0.0", "" -
> if I remember rigth) then the whole expression evaluates to false in
> boolean context.
>
> Whether you use constants or not is irrelevant. You'd see the same
> behaviour with
>
> my @a = (0, 1, 2);
big thanks for explanation :)
PS: My stupid head :D
>
> HTH, Jenda
> ===== je...@krynicky.cz === http://Jenda.Krynicky.cz =====
> When it comes to wine, women and song, wizards are allowed
> to get drunk and croon as much as they like.
> -- Terry Pratchett in Sourcery
>
>
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