in reply to accessing a hash via reference

References: perlreftut, perldsc
     # what is going on here? What am i dealing with?
        print " $token->[2]\n  ";     # how do i dereference this?

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     use Data::Dumper;
     print Dumper $token->[2];
# or w/o Data::Dumper
     print join(":", keys %{$token->[2]}), "\n";

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      my %hash = $token->[2];
        #    below wont work unless i feed it a hash
        #    my $key;
        #    foreach $key (keys %hash) {
        #    print "at $key we have $hash{$key}\n";
        #    }

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      my $hash = $token->[2];
      foreach my $key (keys %$hash) {
          printf "at %s we have %s\n", $key, $hash->{$key};
      }

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Or, alternatively (but the above is better, because this way below makes a copy of the data in the hash): 
      my %hash = %{$token->[2]};
      foreach my $key (keys %hash) {
          printf "at %s we have %s\n", $key, $hash{$key};
      }

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Replies are listed 'Best First'.
Re^2: accessing a hash via reference
by richill (Monk) on Sep 03, 2006 at 13:30 UTC
    Thank you. Thats great.Just one question

    Is the difference between

         my %hash = %{$token->[2]}; and

    my %hash = $token->[2];

    The former trys to assign a string to a hash. Saying something like %hash = HASH(0x86b258)

    The latter assigns a hash to a hash by telling perl that whatever is inside %{} is definately a hash.Perl then gos and gets whatever $token->[2] points to and dereferences it.

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[d/l]
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      Need for <code></code> tags aside, the first is dereferencing a hash ref into a list and then assigning that list to your hash. The second is attempting to assign the hashref to the hash, which will get you a gripe about assigning an odd number of elements to a hash and a hash with one entry with a stringified representation of the hashref (what you're seeing) as the key.

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        Thanks
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