See perldata, first paragraph:

Hashes are unordered collections of scalar values indexed by their associated string key.

So, you can't use any scalar as a hash key, just a string.

There is the module Tie::RefHash though, which allows you to use references as hash keys, which seems to be what you're trying to do.

There is one special kind of hash Tie::RefHash in which we can store reference as keys.
Below is the code i tried,it may help you to store reference as key in a hash.

use Tie::Refhash;
tie %hash 'tie::RefHash';
%hash =( ["one","two"] => "numbers",
         ["pen","book"]=> "stationery");
while(my($keyref,$value)=each %h))
{
  print "@$keyref has $value\n";
}
[download]

#!/usr/bin/perl 
use strict;
use warnings;

my $a=10;
my %b; 

$b{\$a}= $a; 
while ( my ($key, $value) = each %b) { print "$key => $b{$key}\n"; }
[download]

Output:
SCALAR(0x814f5c4) => 10

Err, whatever. Now multiply SCALAR(0x814f5c4) by 2 and tell me the result is 20 :)

• another intruder with the mooring in the heart of the Perl

No but :
print pack('h', 0x814f5c4)
will give you a nice smiling face ☺


{
    use charnames ':full';
    my $smiling_face = "\N{WHITE SMILING FACE}";
}
[download]

Tested under XP and the latest Cygwin

PooLpi ;)