I have looked over perl data type's and I have done a blanket Super Search for hashes, but I came up with nothing.

Here is the code:

use Data::Dumper;

my %h; # intial hash

# put in some random values
$h{'a'}{'1'} = 'z';
$h{'a'}{'2'} = 'y';
$h{'a'}{'3'} = 'x';
$h{'b'}{'4'} = 'w';
$h{'b'}{'5'} = 'u';
$h{'b'}{'6'} = 'v';
$h{'c'}{'7'} = 'r';
$h{'c'}{'8'} = 's';
$h{'c'}{'9'} = 't';

# make an assignment that I assume is by value
my %tmpHash = %h;

# make a change in the temp hash
$tmpHash{'b'}{'6'} = 'j';

print Dumper(%h);

print "\n\n\n";

print Dumper(%x);
[download]

This ends up outputting:

$VAR1 = 'a';
$VAR2 = {
          1 => 'z',
          2 => 'y',
          3 => 'x'
        };
$VAR3 = 'b';
$VAR4 = {
          4 => 'w',
          5 => 'u',
          6 => 'j'
        };
$VAR5 = 'c';
$VAR6 = {
          8 => 's',
          9 => 't',
          7 => 'r'
        };



$VAR1 = 'a';
$VAR2 = {
          1 => 'z',
          2 => 'y',
          3 => 'x'
        };
$VAR3 = 'b';
$VAR4 = {
          4 => 'w',
          5 => 'u',
          6 => 'j'
        };
$VAR5 = 'c';
$VAR6 = {
          8 => 's',
          9 => 't',
          7 => 'r'
        };

As you can see, both hashes are changed. That surprised me. So, I am wondering how do you copy a hash by value. Is a foreach loop the only way to do it?

Jeremy