Difference in accessing a Hash

perl@1983 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks, I have a hash as below:

my $a = {
          b => 1,
          c => 2,
          d => { e => 1 },
        }
[download]

I wanted to know what is the difference when I access above hash using $a{b} vs $a->{b}? Thanks in advance.

Comment on Difference in accessing a Hash Download Code

Replies are listed 'Best First'.
Re: Difference in accessing a Hash by moritz (Cardinal) on Aug 03, 2012 at 13:03 UTC
`$a{b}` accesses the hash `%a`, which has no relation to the variable `$a`. `$a->{b}` assumes that `$a` is a hash reference, and accesses the element `b` of it. Always `use strict`, it will catch such errors if you happen to write the wrong one (and the other one isn't declared). Perl 6 - the future is here, just unevenly distributed	[reply] [d/l] [select]
Re^2: Difference in accessing a Hash by perl@1983 (Sexton) on Aug 03, 2012 at 13:06 UTC
Got it. Thanks moritz for the clarification.	[reply]
Re: Difference in accessing a Hash by locked_user sundialsvc4 (Abbot) on Aug 03, 2012 at 13:37 UTC
Also notice that `$$foo{bar}` ... notice the doubled dollar-sign ... is equivalent to `$foo->{bar}`. The potential problem being of course that a single dollar-sign in this case is also syntactically valid but carries a different meaning. The best thing to do is to adopt a “shop standard” and then stick to it very religiously. `“PARIS IN THE THE SPRING”` and all of that ... heh ... you did see the extra word in there, now, didn’t you?