Tip #1 from the Basic debugging checklist. Your code generates warning messages when you use warnings. Fixing those is a good place to start.

Further to toolic's reply:

if(exists($final->{$x[$i]})){
    print "second\n";
    ($final->{$x[$i]}, $f);
    }
else{
    print "first\n";
    $final->{$x[$i]} = ($final->{$x[$i]}, $f);    
    }
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The statement
    $final->{$x[$i]} = ($final->{$x[$i]}, $f);
is a bit more complex. It evaluates the list  ($final->{$x[$i]}, $f) in the scalar context imposed by the scalar  $final->{$x[$i]} on the LHS of the assignment. I doubt this statement does what you expect. Please see the Context tutorial, in particular the "Context clash" section.

c:\@Work\Perl>perl -wMstrict -MData::Dumper -le
"my $final = { qw(a 1  b 2  c 3), d => [ 9, 8, 7 ] };
 my @x = qw(a b c);
 print 'data to start';
 print Dumper $final;
 print Dumper \@x;
 ;;
 my $f = 'ZOT';
 ;;
 print 'void-context expression';
 ($final->{$x[1]}, $f);
 print Dumper $final;
 ;;
 print 'assign list in scalar context';
 $final->{$x[1]} = ($final->{$x[1]}, $f);
 print Dumper $final;
"
Useless use of hash element in void context at -e line 1.
Useless use of hash element in void context at -e line 1.
Useless use of private variable in void context at -e line 1.
data to start
$VAR1 = {
          'c' => '3',
          'a' => '1',
          'b' => '2',
          'd' => [
                   9,
                   8,
                   7
                 ]
        };

$VAR1 = [
          'a',
          'b',
          'c'
        ];

void-context expression
$VAR1 = {
          'c' => '3',
          'a' => '1',
          'b' => '2',
          'd' => [
                   9,
                   8,
                   7
                 ]
        };

assign list in scalar context
$VAR1 = {
          'c' => '3',
          'a' => '1',
          'b' => 'ZOT',
          'd' => [
                   9,
                   8,
                   7
                 ]
        };
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I think there may be other problems with the script, but this should get you going. Perhaps also see Perl Data Structures Cookbook.

You have re-posted an apparent exact duplicate of the OP of this thread. Please do not re-post such duplicates. Please respond in this thread as to how the advice offered here has or has not helped you, and as to specific new difficulties you may be facing.

Hi,

I made some changes as per my understanding, but i couldn't make changes in the code to reflect as per requirement.

...
if(exists($final->{$x[$i]})){
    print "second\n";
    $final->{$x[$i]} = ($final->{$x[$i]}, $f);  #### i need to push th
+e $f into $final.
}
...
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Current output:

$VAR1 = \{ 'a' => { 'b' => 'abc' } };

Expected Output:

$VAR1 = \{ 'a' => { 'b' => 'abc' }, { 'c' => 'xyz' } };

use strict;
use warnings;
use Data::Dumper;


my $hash;

while (<DATA>){
    my ($left,$val) = split /=/,$_ or next;
    my ($first,@levels) = split /\./,$left;
    
    my $str="\$hash->{$first}";
    
    for my $last_level(@levels){
        $str .= "{$last_level}" 
    }
    eval "$str=$val";
}

print Dumper \$hash;

__DATA__
a.b='xyz'
a.c='abc'
d='def'
a.e='ghi'
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$VAR1 = \{
            'a' => {
                     'e' => 'ghi',
                     'c' => 'abc',
                     'b' => 'xyz'
                   },
            'd' => 'def'
          };
[download]