Re: How to get 0 to initialize a value

[AnomalousMonk]

Others have pointed out that the OPed code seems to work just fine once the
    my $first_novel = $novel_list->[$first_book];
statement is fixed to be
    my $first_novel = $novel_list[$first_book];

Somewhat off-topic, may I suggest that a better approach might be to use a hash:

use strict;
use warnings;

my @novel_list = <DATA>;
chomp @novel_list;

my %characters = (
    Bink => 'M1, M2, m3, m4, 6, m7, M9, m11, m13, 14, 17, m19, m21, M2
+2, m23, m31, 35, 36, m37, m40, m41',
    Quan => '0',
    );

for my $character (sort keys %characters) {

  my @appearances = split m{ \s* , \s* }xms, $characters{$character};

  my $first_book = $appearances[0];
  my $first_type = $first_book =~ /^M/ ? 'major' : $first_book =~ /^m/
+ ? 'mentioned' : undef;
  (my $i_first_novel = $first_book) =~ s/\D+//g;
  my $first_novel = $i_first_novel ? qq{"$novel_list[$i_first_novel]"}
                                   : "[$novel_list[$i_first_novel]]"
                                   ;

  print "$first_novel is the first novel '$character' was in. \n";

  }

__DATA__
Other source
A Spell for Chameleon
The Source of Magic
Castle Roogna
Centaur Aisle
Ogre, Ogre
Night Mare
Dragon on a Pedestal
Crewel Lye: A Caustic Yarn
Golem in the Gears
Vale of the Vole
Heaven Cent
Man from Mundania
Isle of View
Question Quest
The Color of Her
Demons Don't Dream
Harpy Thyme
Geis of the Gargoyle
Roc and a Hard Place
Yon Ill Wind
Faun and Games
Zombie Lover
Xone of Contention
The Dastard
Swell Foop
Up in a Heaval
Cube Route
Currant Events
Pet Peeve
Stork Naked
Air Apparent
Two to the Fifth
Jumper Cable
Knot Gneiss
Well-Tempered Clavicle
Luck of the Draw
Esrever Doom
Board Stiff
Five Portraits
Isis Orb
Ghost Writer in the Sky

Output:

c:\@Work\Perl\monks\Lady_Aleena>perl novel_character_list_2.pl
"A Spell for Chameleon" is the first novel 'Bink' was in.
[Other source] is the first novel 'Quan' was in.

[Lady_Aleena]

I found the problem in my data. I made the assumption my data was correct. I should know better. Sorry for taking up your time.

I took those values OUT of the hash they were in. I wasn't about to post a hash that has 2,198 keys and each of those keys has at least 8 keys. I simplified my code for this problem. And yes, I know I made a mistake with the @novel_list, but the warning still remains. The actual code is...

for my $key (keys %$characters) {
  my $character = $characters->{$key};
  my $name      = $character->{Name};

# about 30 more lines of code to munge the data

  my @novels = split(/, /, $character->{book}); # line 132 in code
  my $first_book = $novels[0];
  my $first_type = $first_book =~ /^M/ ? 'major' : $first_book =~ /^m/
+ ? 'mentioned' : undef; # line 134 in code
     $first_book =~ s/\D//g; # line 135 in code
  $character->{intro}->{book} = $book_list[$first_book]; # line 136 in
+ code
  $character->{intro}->{type} = $first_type;
  $character->{book} = \@novels;

# about 30 more lines of code to munge the data
}

The hash would be (I think)...

my $characters = {
  Bink => {
    Name => 'Bink',
    book => 'M1, M2, m3, m4, 6, m7, M9, m11, m13, 14, 17, m19, m21, M2
+2, m23, m31, 35, 36, m37, m40, m41',
  },
  Quan => {
    Name => 'Quan',
    book => '0',
  },
};

I just didn't feel like making the hash for it. $character->{book} is still coming back uninitialized for Quan.

The errors are...

character_tests.pl: Use of uninitialized value in split at character_t
+ests.pl line 132
character_tests.pl: Use of uninitialized value $first_book in pattern 
+match (m//) at character_tests.pl line 134
character_tests.pl: Use of uninitialized value $first_book in pattern 
+match (m//) at character_tests.pl line 134
character_tests.pl: Use of uninitialized value $first_book in substitu
+tion (s///) at character_tests.pl line 135
character_tests.pl: Use of uninitialized value $first_book in array el
+ement at character_tests.pl line 136

[hippo]

SSCCE:

use strict;
use warnings;

use Test::More tests => 1;
use Test::NoWarnings;

my $characters = {
    Bink => {
        Name => 'Bink',
        book =>
          'M1, M2, m3, m4, 6, m7, M9, m11, m13, 14, 17, m19, m21, M22,
+ m23, m31, 35, 36, m37, m40, m41',
    },
    Quan => {
        Name => 'Quan',
        book => '0',
    },
};
my @book_list;

for my $key (keys %$characters) {
  my $character = $characters->{$key};
  my $name      = $character->{Name};

# about 30 more lines of code to munge the data

  my @novels = split(/, /, $character->{book}); # line 132 in code
  my $first_book = $novels[0];
  my $first_type = $first_book =~ /^M/ ? 'major' : $first_book =~ /^m/
+ ? 'mentioned' : undef; # line 134 in code
     $first_book =~ s/\D//g; # line 135 in code
  $character->{intro}->{book} = $book_list[$first_book]; # line 136 in
+ code
  $character->{intro}->{type} = $first_type;
  $character->{book} = \@novels;

# about 30 more lines of code to munge the data
}