From: PerlFAQ Server on
This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at .


4.74: How do I print out or copy a recursive data structure?

The "Data::Dumper" module on CPAN (or the 5.005 release of Perl) is
great for printing out data structures. The "Storable" module on CPAN
(or the 5.8 release of Perl), provides a function called "dclone" that
recursively copies its argument.

use Storable qw(dclone);
$r2 = dclone($r1);

Where $r1 can be a reference to any kind of data structure you'd like.
It will be deeply copied. Because "dclone" takes and returns references,
you'd have to add extra punctuation if you had a hash of arrays that you
wanted to copy.

%newhash = %{ dclone(\%oldhash) };


The perlfaq-workers, a group of volunteers, maintain the perlfaq. They
are not necessarily experts in every domain where Perl might show up,
so please include as much information as possible and relevant in any
corrections. The perlfaq-workers also don't have access to every
operating system or platform, so please include relevant details for
corrections to examples that do not work on particular platforms.
Working code is greatly appreciated.

If you'd like to help maintain the perlfaq, see the details in