How to keys($array

networker2149 has asked for the wisdom of the Perl Monks concerning the following question:

according to perl doc the keys() function will take a reference stored in a scalar, but it doesn't seem to work for me. I printed my reference to make sure it's really a reference but it still doesn't seem to work. Does keys() take a reference? If so I'll check my syntax.


$returns{'do_stuff'} = &do_stuff;

my $ref99 = $returns{'do_stuff'}->[2]
print keys($returns{'do_stuff'}->[2] ) , "\n";
print keys($ref99) , "\n";


sub do_stuff {
   my $ip = "198.18.0.210";
   my $uname = "admin";
   my $pass = "admin1";
   my $cmd = "show chassis fpc pic-status | no-more";
   my $ssh;
   my @output;
   my @out_lines;
   my @pics;
   my @fpcs;
   my %chassis;
   my $reachable;
   my $hostname = "mx480-0-re0";
   my $err;
   my $exit;


#doing stuff....

my @returns = (0 , "Success" , \%chassis , \@fpcs);
return(\@returns);
}
[download]

here's the Hash in question dumperer'd. It's actually a hash-of-arrays-of-hashes-of-arrays.

$VAR1 = 'do_stuff';
$VAR2 = [
          0,
          'Success',
          {
            'Slot 1' => [
                          'PIC 0',
                          'PIC 1',
                          'PIC 2',
                          'PIC 3'
                        ],
            'Slot 0' => [
                          'PIC 0',
                          'PIC 1',
                          'PIC 2',
                          'PIC 3'
                        ]
          }
        ];
[download]

Comment on How to keys($array_ref)? Select or Download Code

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Re: How to keys($array_ref)? by ikegami (Patriarch) on Sep 14, 2011 at 18:49 UTC
according to perl doc the keys() function will take a reference stored in a scalar Since 5.14, yes. (And it has to be an unblessed reference.) Before that, it was a compile time error.	[reply]
Re: How to keys($array_ref)? by moritz (Cardinal) on Sep 14, 2011 at 17:43 UTC
When you test the syntax of a perl expression, start off with simple cases: `$ perl -wE 'say keys [1, 2]' 01 $ perl -wE 'say keys { a => 1, b => 2 }' ab` [download] So, works fine. Something seems to be off in your code, reducing it to a few essential lines probably shows the problem more clearly. It also generally helps if you're more specific than "doesn't seem to work" -- do you get an error message, or some wrong result? What do you expect, what do you get? Update: I removed some irrelevant parts from your code, and got an empty line, which makes sense since you haven't posted any code that initializes %chassis. When I add some initialization, it works as expected: `$returns{'do_stuff'} = do_stuff(); print keys($returns{'do_stuff'}->[2] ) , "\n"; sub do_stuff { my %chassis = ( a => 1, b => 2 ); my @returns = (0 , "Success" , \%chassis); return(\@returns); } __END__ ab` [download] (Tested with perl 5.14.1). Perl 6 - second systems done right	[reply] [d/l] [select]
Re^2: How to keys($array_ref)? by networker2149 (Novice) on Sep 17, 2011 at 02:36 UTC
Figured it out. I was accidentally creating a second reference in the return array with `my @returns = ["blah","blah","blah"]; return(\@returns);` [download] which should have been: `my @returns = ("blah","blah","blah"); return(\@returns);` [download] so I ended up with a reference to a reference to the array I was trying to access instead of a reference to the data.	[reply] [d/l] [select]
Re: How to keys($array_ref)? by muba (Priest) on Sep 14, 2011 at 23:01 UTC
On a side note, I feel I should mention that tthe title of your node is slightly confusing. You're trying to get the keys of a hashref (namely, a reference to hash called %chassis in do_stuff), not of an arrayref.	[reply]
Re^2: How to keys($array_ref)? by networker2149 (Novice) on Sep 17, 2011 at 02:38 UTC
sorry about that. I have been modifying this code too much and haven't cleaned up. At one point that variable actually was an array reference. I probably should have fixed it before I posted it online. Thanks all for the help though.	[reply]