How do I create a hash of hashes in Perl?

Question

Based on my current understanding of hashes in Perl, I would expect this code to print \"hello world.\" It instead prints nothing.

%a=();

%b=();
$b{str} = \         


        

Answer 1

1. You should always use "use strict;" in your program.

2. Use references and anonymous hashes.

use strict;use warnings;
my %a;

my %b;
$b{str} = "hello";  
$a{1}={%b};

%b=();
$b{str} = "world";
$a{2}={%b};

print "$a{1}{str}  $a{2}{str}";

{%b} creates reference to copy of hash %b. You need copy here because you empty it later.