satzbu:

You might want to try reading perlsyn so you can review the syntax of the for and foreach statement. Because you omitted the (necessary) parenthesis, perl doesn't want to compile your program. Of course, when you fix that one, it'll then whine about your usage of $xhash in the same line. You want that line to read:

foreach (keys(%xhash)) {
[download]

...roboticus

If I'm understanding you correctly (i.e. that key names should be changed to the value indicated by 'replval' => ... in the respective %c_hash entry, if such an entry exists), you want something like this:

#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

my %xhash = ('a' => {
                 'b' => {
                        'e' => 'E',
                        'c' => 'C',
                        'content' => 'B
'
                      },
                 'content' => 'A
',
                 'd' => 'D'
               });

my %c_hash=('a' => {
                   'addval' => {
                                 'b' => {
                                          'addval' => {
                                                        'e' => {
                                                                 'addv
+al' => {},
                                                                 'repv
+al' => '5'
                                                               },
                                                        'c' => {
                                                                 'addv
+al' => {},
                                                                 'repv
+al' => '3'
                                                               }
                                                      },
                                          'repval' => '2'
                                        },
                                 'd' => {
                                          'addval' => {},
                                          'repval' => '4'
                                        }
                               },
                   'repval' => '1'
                 });


sub traverse {
    my ($hash, $callback, $mode) = @_;
    return unless ref($hash) eq "HASH";
    for my $key (keys %$hash) {
        my $val = $hash->{$key};
        if (ref($val) eq "HASH") {
            traverse($val, $callback, $mode);
            if ($mode eq "collect") {
                if (exists $val->{repval}) {
                    $callback->($key, $val->{repval});
                }
            }
        }
        if ($mode eq "replace") {
            $callback->($key, $val, $hash);
        }
    }
}

my %repl;  # lookup table: a => 1, etc.
traverse(\%c_hash,
         sub {
             my ($key, $val) = @_;
             $repl{$key} = $val;
         },
         "collect"
);
# print Dumper \%repl;  # debug

traverse(\%xhash,
         sub {
             my ($key, $val, $href) = @_;
             if (exists $repl{$key}) {
                 my $newkey = $repl{$key};
                 $href->{$newkey} = $val;
                 delete $href->{$key};
             }
         },
         "replace"
);
print Dumper \%xhash;

__END__
$VAR1 = {
          '1' => {
                   '4' => 'D',
                   'content' => 'A
',
                   '2' => {
                            '3' => 'C',
                            'content' => 'B
',
                            '5' => 'E'
                          }
                 }
        };
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Note that as you can't rename hash keys, you have to create new key-value pairs (new key, old value), while deleting the old entries.

mam when i change my input hash as the grouping means it cant replace the keys what changes i made on that code please tell mam its very urgent this is my input

my %xhash = ('a' => [{
                 'b' => [{
                        'e' => 'E',
                        'c' => 'C',
                        'content' => 'B
'
                      }],
                 'content' => 'A
',
                 'd' => 'D'
               }]);
[download]

Either use $_ as the key to your hash in the loop or explicitly specify foreach my $k keys($xhash)

I think the real problem here is the missing parens

foreach ( keys(%xhash) ) {
[download]

because of which Perl interprets keys as a variable name, and complains about the missing sigil...  —> use diagnostics;

Also, it should be %xhash, not $xhash.