use strict;
use warnings;
my %description = ( a => 'a vowel',
                    b => 'a consonant',
                    0 => '0',
                    default => 'not in the alphabet' );

for my $char (qw/a b c 0/) {
   my $d = $description{$char} || $description{default};
   print("$char is $d\n");
}