#!/usr/bin/perl
use strict;

sub handler {
	my %foo=(a=>1,b=>2,c=>3);
	a(\%foo);
	print "A -> $foo{a} B -> $foo{b} C -> $foo{c}\n" ;
}

sub a 
{
	my $ref=shift;
	$ref->{a} = 100;
	my %copy=%$ref;
	$copy{a} = 10;
	my $ptr =\$ref->{b};
	$$ptr = 20;
}