in reply to deep copy of hash of hash

my $y = {%x};

Although this does create a reference to a new anonymous hash and copies the key/value pairs (you can modify the keys of %$y without affecting the set of keys in %x), this is still not a deep copy - the values are still references to the same nested hashes ({'lastname' => 'michael','tel'=>'222'}) as in the original data structure.

For true deep copies, see e.g. dclone from Storable or Clone.

Minor improvements to wording.

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Re^2: deep copy of hash of hash
by cmic (Acolyte) on May 27, 2019 at 09:25 UTC
    I get it. However, I loaded CPAN Clone module, but as I 
    use Clone 'Clone'; 
#or even: 
use Clone::More qw( clone );

    [download]
    Perl -c answers: "Clone" is not exported by the Clone module What should I do? (sorry to be a bit noob there...) TYA
    -- cmic. Life helps. Perl Too.
[reply]
[d/l]

      Perl is case sensitive. Here is an SSCCE:

      use strict;
use warnings;

use Test::More tests => 2;
use Clone 'clone';

my %x = (
    miller => {lastname => 'michael', tel => '222'},
    duran  => {lastname => 'peggy',   tel => '333'},
); 
my %y = %{clone (\%x)};
is_deeply (\%x, \%y);

$x{duran}{tel} = '444';
isnt ($x{duran}{tel}, $y{duran}{tel});

      [download]
[reply]
[d/l]

      The documentation says Use Clone 'clone'; (note the lower case) but you have asked to import Clone with an initial upper case letter. I can't test as I don't have that module but perhaps that is your problem.

      Cheers,

      JohnGG

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