CODEWITHSUNDEEP
perl
user2312562
user2312562

Reputation: 11

Can't print the size of a hash of hashes or access element within it

I have a hash %AllData pulling data from database using following code:

while(my $Row = $sth1->fetchrow_hashref())
        {
            if(defined($Row->{LotID}))
            {
                    $AllData->{$Row->{LotID}}->{$Row->{Name}} = $Row->{Details};
            }
        }

After I'm done with pulling data, I use print Dumper($AllData); to print out All my data which show like:

$VAR1 = {
          '4197359' => {
                         'Short Description' => 'Rock Picker',
                         'Lot Number' => '1065',
                         'Description' => 'Rock Picker'
                       },
          '4194148' => {
                         'Short Description' => 'Large work bench w/ drawers',
                         'Lot Number' => '1041',
                         'Description' => 'Large work bench w/ drawers'
                       },
          '4200944' => {
                         'Lot Number' => '1084',
                         'Description' => 'Horse Trailer'
                       }
}

However, when I try to print out the size of the hash or use foreach to access the hash, it shows 0 size and can't access any element within the hash:

print "Hash Size: ", scalar keys %AllData, "\n";

shows:

Hash Size: 0

What's the cause of my problem?

Upvotes: 1

Views: 373

Answers (4)

Rahul Reddy
Rahul Reddy

Reputation: 13163

should represent a hash ref as $%hash instead of %hash to print

Upvotes: 0

Jon Carter
Jon Carter

Reputation: 3436

Try accessing scalar keys %$AllData in order to access the hash that the reference.. refers to.

  • $AllData (what you're passing to Dumper() ) is a reference to a hash (a 'hashref')

  • %AllData is a different thing to Perl than $AllData. If this hasn't been set yet and perl isn't complaining, you may need to try putting use strict; at the top of your script so that you can be warned of these (and other) types of errors.

Upvotes: 4

Borodin
Borodin

Reputation: 126742

There is no hash %AllData, and if your program didn't raise an error then you haven't got

use strict;
use warnings;

at the head of you program. This is vital for all Perl programs, especially when you are asking others for help with your code.

The hash you're interested in is the one referenced by $AllData, so you need to use this variable and dereference it. Like this

print "Hash Size: ", scalar keys %$AllData, "\n";

Upvotes: 6

toolic
toolic

Reputation: 62154

Maybe you need to dereference the hash first:

print "Hash Size: ", scalar keys %{ $AllData }, "\n";

Upvotes: 2

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