The two are identical: perl specifically allows $x{a}{b} as shorthand for $x{a}->{b}. Which you use is a matter of personal preference or house style.

Note that this shorthand is available only for the second (or subsequent) dereference: $x{a} and $x->{a} are different, the first looking up a key in the hash %x while the second looks up a key in the hash reference $x.

They are the same, you should use whichever you prefer. Some people think the arrow makes it clearer that you're dealing with a reference. Some people think it's visual noise.

You can also omit the arrow when dereferencing a nested array (eg: $s{a}[1]).

There is one thing to watch out for though. In your case, you have a hash called %x. If you had a hashref $x instead then the initial arrow would not be optional. You'd need to use either $x->{a}{b} or $$x{a}{b}.

There is no difference: that is a bit of syntactic sugar for multilevel data structures. All such structures in perl are built from references, so the compiler doesn't need the arrow to know that dereference is needed.

After Compline,
Zaxo

To quote the camel book, "The arrow is optional between brackets or braces, or between a closing bracket or brace and a parenthesis for an indirect function call."

So basically it's whatever you prefer. I like to leave the arrow out because it's less to type, but if you think it looks better to leave it in, that works too.

     # The $x is a hashreference and here :

      my $ones = {};

      $ones{a}={b=>1};

      print "[$ones{a}]\n";
      print "[$ones->{a}]\n";
      print "[$ones{a}->{b}]\n";
      print "[$ones{a}{b}]\n";


    __END__

    [HASH(0xe01d8)]
    []
    [1]
    [1]
[download]