You are passing addtwo() an array reference (the square brackets []), but treating it like a hash reference (by using $params->{structure}). You might need to read up on perlref.

Along with having an array reference as opposed to a hash reference, ref($aref) returns ARRAY, not LIST, so that'll never catch.

Here's a basic example for review and to do some testing with:

use warnings;
use strict;

my $struct = [
    {
        1 => 'a',
        2 => 'b',
    },
    [
        1,
        2,
        3,
    ],
    {
        3 => 'c',
        4 => 'd',
    },
];

thing($struct);

sub thing {
    my ($aref) = @_;

    for my $elem (@$aref){
        if (ref $elem eq 'ARRAY'){
            print "array:\n";
            print "$_\n" for @$elem;
        }
        elsif (ref $elem eq 'HASH'){
            print "hash:\n";
            print "$_ => $elem->{$_}\n" for keys %$elem;
        }
        else {
            die "element is not an allowed ref\n";
        }
    }
}
[download]

Output:

hash:
1 => a
2 => b
array:
1
2
3
hash:
3 => c
4 => d
[download]

#!/usr/bin/perl -l

# http://perlmonks.org/?node_id=1180347

use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Terse = 1;
$Data::Dumper::Indent = 0;

sub addone
  {
  my $arg = shift;
  ref $arg eq 'ARRAY' ? [ map addone($_), @$arg ] :
    ref $arg eq 'HASH' ? { map addone($_), %$arg } :
    $arg =~ /^\d+\z/ ? $arg + 1 : $arg;
  }

print Dumper addone( [ { a => 1, b => 2, c => 3  }, { d => 4, e => 5 }
+,
  [ 6, 7, 8 ], 9, 10, 11, [ 12, 13, 14 ] ] );
[download]

I am still struggling with this code .. i cant figure out much after going through documentation ... this method works whats the error in this ..

#!/usr/bin/perl
use strict;
use warnings 'all';
    my    $structure = [ { a => 1, b => 2, c => 3 }, { d => 4, e => 5 
+}, [ 6, 7, 8 ], 9, 10, 11, [ 12, 13, 14 ] ];
    
    sub addtwo {
        
    my $params = shift;
     my $s = $params->{$structure};
    
    if (ref($s) eq "ARRAY") {
         my $c = 0;
        foreach my $e (@{$s}) {
            $s->[$c] = addtwo({ structur => $e });
            $c++;
        } 
    } elsif (ref($s) eq "HASH") {

        if (scalar keys %{$s} == 0) {
            return undef;
       } else {
            foreach my $e (values %{$s}) {
                $s->{$e} = addtwo({ structure => $s->{$e} });
            }
        }
    
    } else {
        $s = 1;
    }
    
    return my $c;
}
[download]

A hash key is always a string. What do you the following does when $structure is an array reference?

my $s = $params->{$structure};
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

What is the error message?