perlの配列・ハッシュのリファレンス

#--------------------------------
#hash referance
%hash = (a=>100,b=>200,c=>300);
$ref_hash=\%hash;

print $ref_hash->{a}."\n";
print ${$ref_hash}{b}."\n";
%hash2 = %{$ref_hash};
print $hash2{c}."\n";

#--------------------------------
#array referance 
@array=(1,2,3,4,5);
$ref_array = \@array;

print $ref_array->[0]."\n";
print ${$ref_array}[1]."\n";
@array2 = @{$ref_array};
print @array2[2]."\n";