Elements added to hash in for loop

nathaniels has asked for the wisdom of the Perl Monks concerning the following question:

Hello!

I've been working on this for a while and I'm absolutely dumbfounded. This function is supposed to search through a hash created from a database pull by searching through the primary keys. However, after an iteration through the loop two entries get added: 0 => {}, 1 => {}. Here's the function:


use DBI;
use List:Util;
use Math::Complex;

my %CLAUSES;

sub next_clauseid {

    my $current_id = @_;
  
    foreach my $id ( keys %CLAUSES ) {
    
    
        if ( $CLAUSES{ $id }{ lineno } ==  $CLAUSES{ $current_id }{ li
+neno }
            and $CLAUSES{ $id }{ clauseno } == ($CLAUSES{ $current_id 
+}{ clauseno } + 1) ) {
            return $id;  
        }
    }
    return 0;
}
[download]

Some sample data in %CLAUSES

  10950,
  {
    behav_behaver    => undef,
    behavioural      => undef,
    character        => "MARS",
    clause           => "Did you just swear?",
    clauseid         => 10950,
    clauseno         => 1,
    exist_existent   => undef,
    existential      => undef,
    lineid           => 181,
    lineno           => 181,
    mat_actor        => undef,
    mat_goal         => undef,
    material         => undef,
    men_phenom       => undef,
    men_senser       => undef,
    mental           => undef,
    rel_attribute    => undef,
    rel_carrier      => undef,
    rel_identified   => undef,
    rel_identifier   => undef,
    relational_attr  => undef,
    relational_ident => undef,
    verb_sayer       => undef,
    verb_target      => undef,
    verbal           => undef,
  },
  10736,
  {
    behav_behaver    => undef,
    behavioural      => "",
    character        => "BRIAN",
    clause           => "Yeah, yeah.",
    clauseid         => 10736,
    clauseno         => 1,
    exist_existent   => "",
    existential      => "",
    lineid           => 7,
    lineno           => 7,
    mat_actor        => "",
    mat_goal         => "",
    material         => "",
    men_phenom       => "",
    men_senser       => "",
    mental           => "",
    rel_attribute    => "",
    rel_carrier      => "",
    rel_identified   => "",
    rel_identifier   => "",
    relational_attr  => "",
    relational_ident => "",
    verb_sayer       => "",
    verb_target      => "",
    verbal           => "",
  },
  10862,
  {
    behav_behaver    => undef,
    behavioural      => undef,
    character        => "BRIAN",
    clause           => "I'll call the cops.",
    clauseid         => 10862,
    clauseno         => 1,
    exist_existent   => undef,
    existential      => undef,
    lineid           => 121,
    lineno           => 121,
    mat_actor        => undef,
    mat_goal         => undef,
    material         => undef,
    men_phenom       => undef,
    men_senser       => undef,
    mental           => undef,
    rel_attribute    => undef,
    rel_carrier      => undef,
    rel_identified   => undef,
    rel_identifier   => undef,
    relational_attr  => undef,
    relational_ident => undef,
    verb_sayer       => undef,
    verb_target      => undef,
    verbal           => undef,
  },
[download]

Thanks for your help!

Comment on Elements added to hash in for loop Select or Download Code

Replies are listed 'Best First'.
Re: Elements added to hash in for loop by LanX (Saint) on Dec 13, 2013 at 03:42 UTC
try including parens `my ($current_id) = @_;` [download] otherwise you are using the length of @_ as key and autovivification creates new entries. Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re^2: Elements added to hash in for loop by AnomalousMonk (Archbishop) on Dec 13, 2013 at 10:59 UTC
... you are using the length of @_ as key ... nathaniels: This raises the question: Under what circumstances are you calling the `next_clauseid()` function with zero parameters?!? I hope that you `usewarnings` so that if you employ the common parameter passing conventions advised by LanX and 2teez, you will at least receive a warning message from Perl in case of such a lapse.	[reply] [d/l] [select]
Re^3: Elements added to hash in for loop by LanX (Saint) on Dec 13, 2013 at 15:15 UTC
I'm not nathaniels, but ... > I hope that you use warnings so that if you employ the common parameter passing ... you will at least receive a warning message from Perl in case of such a lapse. which warning? `DB<102> use warnings;use strict; sub tst { my $scalar=@_; print $sca +lar } DB<103>` [download] =) Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re^4: Elements added to hash in for loop by AnomalousMonk (Archbishop) on Dec 13, 2013 at 20:39 UTC
Re^3: Elements added to hash in for loop by nathaniels (Acolyte) on Dec 14, 2013 at 23:56 UTC
Where can I find these conventions?	[reply]
Re^4: Elements added to hash in for loop by AnomalousMonk (Archbishop) on Dec 15, 2013 at 00:27 UTC
Re^5: Elements added to hash in for loop by nathaniels (Acolyte) on Dec 15, 2013 at 16:49 UTC
Re^2: Elements added to hash in for loop by nathaniels (Acolyte) on Dec 13, 2013 at 04:27 UTC
I knew it had to be something simple! Thanks for your help!	[reply]
Re: Elements added to hash in for loop by 2teez (Vicar) on Dec 13, 2013 at 05:10 UTC
Or something like: `sub next_clauseid { my $current_id = shift(@_); ...` [download] Note the usage of shift If you tell me, I'll forget. If you show me, I'll remember. if you involve me, I'll understand. --- Author unknown to me	[reply] [d/l]
Re: Elements added to hash in for loop by Laurent_R (Canon) on Dec 13, 2013 at 07:51 UTC
Or yet simpler: `my $current_id = shift;` [download]	[reply] [d/l]