#!/usr/bin/perl -w
use strict;
use Data::Dump qw(pp);
use Data::Dumper;

my %totalhash;

# the value of $totalhash{hello1}{world} is a reference
# to an array, a HoHoA

$totalhash{hello1}{world} = ["hello world", "hello2", "hello3"];

# I would not do this, ie make a single value instead of a ref to
# array... make all of the values ref to array even if there
# is only one value for some ...makes the structure more "consistent".
# I just show it as a possibility.
# 
$totalhash{diffHello}{world} = "different hello";  

print "@{$totalhash{hello1}{world}}\n";  # ** need curly braces 
                                         # not ()!!
#prints: hello world hello2 hello3

# I personally would prefer the arrow notation which makes it
# more clear to me that this a reference to array, but you 
# can leave that out if you wish.. Here this is a minor point.

print $totalhash{hello1}{world}->[1],"\n"; 
#prints: hello2

print pp \%totalhash;
print "\n";

# the pp option to Data::Dump is very good, but
# since Data::Dump is not a core module and requires installation,
# this can be problematic.
# Data::Dumper is available on all Perl systems and is "core"

print Dumper \%totalhash;

__END__
#### All print statements: ###
hello world hello2 hello3
hello2
{
  diffHello => { world => "different hello" },
  hello1    => { world => ["hello world", "hello2", "hello3"] },
}
$VAR1 = {
          'diffHello' => {
                           'world' => 'different hello'
                         },
          'hello1' => {
                        'world' => [
                                     'hello world',
                                     'hello2',
                                     'hello3'
                                   ]
                      }
        };