Hope this helps you...
#!/usr/bin/perl -w
# formatted with perltidy
use warnings; # I always use this
use strict;
my %required_list = (
life_jacket => 'preserver',
lotion => 'sunscreen',
water => 'water_bottle',
coat => 'jacket',
);
my %captain = (
name => 'skipper',
life_jacket => 'preserver',
lotion => 'sunscreen',
water => 'water_bottle',
shirt => 'blue_shirt',
coat => 'jacket',
hat => 'cap',
);
my %mate = (
name => 'gilligan',
shirt => 'red_shirt',
hat => 'cap',
socks => 'lucky_socks',
water => 'water_bottle',
);
my %passenger = (
name => 'professor',
lotion => 'sunscreen',
water => 'water_bottle',
calculator => 'slide_rule',
power_supply => 'batteries',
entertainment => 'radio',
);
my @crew = ( \%captain, \%mate, \%passenger );
check_required_items( @crew );
sub check_required_items
{
foreach my $person ( @crew )
{
my $who = ${ $person }{ 'name' };
my @keys = keys %required_list;
foreach ( @keys )
{
# Two variables to see it clearly
my $a1 = $required_list{ "$_" };
my $a2 = ${ $person }{ "$_" };
# Initialize $a2 if it's missing, to avoid warning
$a2 = " " if not $a2;
unless ( $a1 eq $a2 )
{
print "$who is missing $_\n";
}
} ## end foreach ( @keys )
} ## end foreach my $person ( @crew ...
} ## end sub check_required_items
On Sun, May 3, 2009 at 1:53 PM, Thomas H. George <li...@tomgeorge.info>wrote:
> I am inching my way through INTERMEDIATE PERL and tried using hashes to
> solve Chapter 4, Problem 2. I never used hashes before but my attempted
> solution convinced me of their value as contrasted to the solution with
> arrays.
>
> The Problem: My solution works but with an error I can't eliminate.
>
> The difficulty is in the next to last line, the 'unless ...' statement
> which causes warning:
>
> Use of uninitialized value in string eq at chap4-take6.pl line 49.
