The Data::Dumper for hashes is much more readable when you dump a reference to a hash (for example \%site) instead of the hash itself.

The Data::Dumper->Dump() (and ->Dumpxs(), identical functionality but implemented in C so faster) methods can provide more readable output as they allow you to name your variables and allow you to show that a hash really is a hash, not a hash reference. Here are a couple of examples showing the differences as applied to a hash and a hash reference.

use strict;
use warnings;

use Data::Dumper;

my %hash = (
   name => q{Fred},
   age  => 27,
   );

print q{-} x 30, qq{\n};

print Dumper( %hash );
print q{-} x 30, qq{\n};

print Dumper( \ %hash );
print q{-} x 30, qq{\n};

print Data::Dumper->Dump( [ \ %hash ], [ qw{ *hash } ] );
print q{=} x 30, qq{\n};

my $hashRef = {
   name => q{Mary},
   age  => 25,
   };

print Dumper( $hashRef );
print q{-} x 30, qq{\n};

print Data::Dumper->Dump( [ $hashRef ], [ qw{ hashRef } ] );
print q{-} x 30, qq{\n};
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Here is the output.

------------------------------
$VAR1 = 'name';
$VAR2 = 'Fred';
$VAR3 = 'age';
$VAR4 = 27;
------------------------------
$VAR1 = {
          'name' => 'Fred',
          'age' => 27
        };
------------------------------
%hash = (
          'name' => 'Fred',
          'age' => 27
        );
==============================
$VAR1 = {
          'name' => 'Mary',
          'age' => 25
        };
------------------------------
$hashRef = {
             'name' => 'Mary',
             'age' => 25
           };
------------------------------
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I hope this is helpful.

Cheers,

JohnGG

print Dumper(\%usage);
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than to use a loop:

for (keys %usage) { print "$_ = $usage{$_}\n" }
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The real power is if you have a more complicated data structure, such as a hash-of-arrays, a hash-of-hashes, or any arbitrarily deep structure (see perldsc). You don't need to know what the structure is: Dumper figures it out for you. There is no need for nesting loops just to print out the contents.

This is just one usage of the module (the one that your code uses). There are many more purposes and features which you can read about in Data::Dumper.

Perhaps "modules" (emphasis supplied) is merely a typo, but if not, then this clarification:

For your purposes, Dumper is a function within Data::Dumper; not a different module.

See the doc moritz cited, Data::Dumper.

First of all, welcome to the Monastery. Hang around her long enough and you'll learn how to write Perl code the right way. It's helped me.

Two tips: I use Data::Dumper for checking variable values in Web environments, often live sites in emergencies. So, 1) I use:

print "Content-type: html/text\n\n";
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to show the values, but still print the page to the browser. If I really want to stay below the radar, I open up a file on the server and dump the values there.

Nothing revolutionary, but nice to know when starting out with the module.