for loop error

satzbu has asked for the wisdom of the Perl Monks concerning the following question:

please help me to debug this error i have an error report like missing $ on loop at hashreplace.pl this is my code

#!/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 $key = keys(%xhash);
     print $key;
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'
                 });
     print $c_hash{'a'}{'repval'};
     foreach keys($xhash){
     keys(%xhash)=$c_hash{'$key'}{'repval'};
     print Dumper $xhash;}
[download]

i want to replace xhash keys against c_hash values i mean this output only i want

%xhash = ('1' => {
                 '2' => {
                        '5' => 'E',
                        '3' => 'C',
                        'content' => 'B
'
                      },
                 'content' => 'A
',
                 '4' => 'D'
               });
[download]

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Re: for loop error by roboticus (Chancellor) on Apr 13, 2010 at 11:32 UTC
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 $xhash in the same line. You want that line to read: `foreach (keys(%xhash)) {` [download] ...roboticus	[reply] [d/l] [select]
Re: for loop error by almut (Canon) on Apr 13, 2010 at 12:54 UTC
If I'm understanding you correctly (i.e. that key names should be changed to the value indicated by `'replval' => ...` in the respective `%c_hash` entry, if such an entry exists), you want something like this: #!/usr/bin/perl use warnings; use strict; use Data::Dumper; my %xhash = ('a' => { 'b' => { 'e' => 'E', 'c' => 'C', 'content' => 'B ' }, 'content' => 'A ', 'd' => 'D' }); my %c_hash=('a' => { 'addval' => { 'b' => { 'addval' => { 'e' => { 'addv +al' => {}, 'repv +al' => '5' }, 'c' => { 'addv +al' => {}, 'repv +al' => '3' } }, 'repval' => '2' }, 'd' => { 'addval' => {}, 'repval' => '4' } }, 'repval' => '1' }); sub traverse { my ($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__ $VAR1 = { '1' => { '4' => 'D', 'content' => 'A ', '2' => { '3' => 'C', 'content' => 'B ', '5' => 'E' } } }; [download] Note that as you can't rename hash keys, you have to create new key-value pairs (new key, old value), while deleting the old entries.	[reply] [d/l] [select]
Re^2: for loop error by satzbu (Acolyte) on Apr 21, 2010 at 03:49 UTC
mam when i change my input hash as the grouping means it cant replace the keys what changes i made on that code please tell mam its very urgent this is my input `my %xhash = ('a' => [{ 'b' => [{ 'e' => 'E', 'c' => 'C', 'content' => 'B ' }], 'content' => 'A ', 'd' => 'D' }]);` [download]	[reply] [d/l]
Re: for loop error by apl (Monsignor) on Apr 13, 2010 at 11:23 UTC
You use `foreach keys($xhash)` Either use `$_` as the key to your hash in the loop or explicitly specify `foreach my $k keys($xhash)`	[reply] [d/l] [select]
Re^2: for loop error by almut (Canon) on Apr 13, 2010 at 11:37 UTC
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`.	[reply] [d/l] [select]