Question

Now i am modifying the code a little
I am using the code for creating hash haivng duplicate keys. Its giving the syntax error.

use strict;
use warnings;
my $s = "12   A    P1  
23   B    P5
24   C    P2
15   D    P1
06   E    P5";
my $hash;
my @a  = split(/\n/, $s);
foreach (@a)
{
  my $c = (split)[2];
  my $d = (split)[1];
  my $e = (split)[0];
  push(@{$hash->{$c}}, $d);
}
print Dumper($hash );

i am getting the output as

    $VAR1 = {
          'P5' => [
                    'B',
                    'E'
                  ],
          'P2' => [
                    'C'
                  ],
          'P1' => [
                    'A',
                    'D'
                  ]
        };

But i want the output like

    $VAR1 = {
      'P5' => {
      'E' => '06',
      'B' => '23'
     },
     'P2' => {
      'C' => '24'
    },
    'P1' => {
      'A' => '12',
      'D' => '15'
      }
     };

How to do that

Answer 1

Perl is telling you exactly what is wrong. You have used the strict pragma, so using the %hash variable without declaring it is a syntax error. While the string %hash does not appear in your code, the string $hash{...} does, on each of the problem lines. This is the syntax to access an element of the %hash, which is why strict is complaining.

You have declared the variable $hash, so accessing an element of the contained hash reference is written $$hash{...} or $hash->{...}. Fix the problem lines to access the correct variable and the code will compile.