Hashes

Using Arrays and Hashes

Using arrays and hashes in Perl is easy. Complexity begins when you continue to work with references to these data types (Find some examples below).

It can be powerful to combine the array and hash data type. For example you might assign a reference of an array to a hash key: $hash{'foo'} = \@array;
The benefit of the performance might be worth the cost of complexity.

Recursion is of unlimited depth as the general philosophy in Perl itself.

Nested Hashes in Perl

[ Playing with hashes ]

#!/usr/bin/perl -w

use strict;

my %myhash = (

 "image" => {
         "version"      => "" ,
         "name"         => "DSCN4757" ,
         "type"         => "jpg" ,
         "raw_width"    => "" ,
         "raw_height"   => "" ,
         "width"        => "" ,
         "height"       => "" ,
         "resizedName"  => "DSCN4757.sized" ,
} ,
 "thumbnail" => {
         "version"      => "" ,
         "name"         => "DSCN4757.thumb" ,
         "type"         => "jpg" ,
         "raw_width"    => "" ,
         "raw_height"   => "" ,
         "width"        => "" ,
         "height"       => "" ,
         "caption"      => "DSCN4757" ,
} ,
 "itemCaptureDate" => {
         "hours"        => "21" ,
         "minutes"      => "52" ,
         "seconds"      => "59" ,
         "mday"         => "12" ,
         "mon"          => "06" ,
         "year"         => "2003" ,
         "uploadDate"   => "" ,
         "clicks"       => "" ,
} ,

"highlight" => {}

);

print "---> ", $myhash{'image'}->{'resizedName'}, "\n";

Playing with hashes


my $categ = &CATEG();

print $categ->{'fookey'}[0]; # prints out 'aa'

sub CATEG () {
	my @array1 = qw ( aa bb cc );
	my @array2 = qw ( ddd eee fff );

	my %hash = (
		fookey => \@array1 ,
		barkey => \@array2
	);

	\%hash;
}