Maps (aka Associative Arrays)

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Maps1.pl

#!/usr/bin/env perl
use utf8;
use Utils;
use strict;
use warnings;

MAIN:
{
	my $dictionary = {};

	print "dictionary size: ", scalar(keys(%$dictionary)), "\n";
	print "dictionary is ", (!scalar(%$dictionary) ? "empty" : "not empty"), "\n";
	$dictionary->{"apple"} = "red";
	$dictionary->{"banana"} = "yellow";
	$dictionary->{"cantaloupe"} = "orange";
	$dictionary->{"dragonfruit"} = "red";
	$dictionary->{"elderberry"} = "purple";

	print "dictionary size: ", scalar(keys(%$dictionary)), "\n";
	print "dictionary is ", (!scalar(%$dictionary) ? "empty" : "not empty"), "\n";

	print "bananas are ", $dictionary->{"banana"}, "\n";

	my $x = "dragonfruit";
	if (exists $dictionary->{$x}) {
		print $x, " are ", $dictionary->{$x}, "\n";
	} else {
		print "Can't find ", $x, "\n";
	}

	$x = "fig";
	if (exists $dictionary->{$x}) {
		print $x, " are ", $dictionary->{$x}, "\n";
	} else {
		print "Can't find ", $x, "\n";
	}

	$x = "elderberry";
	delete($dictionary->{$x});
	if (exists $dictionary->{$x}) {
		print $x, " are ", $dictionary->{$x}, "\n";
	} else {
		print "Can't find ", $x, "\n";
	}

	print Utils::mapToString($dictionary), "\n";
}

Output

$ perl Maps1.pl dictionary size: 0 dictionary is empty dictionary size: 5 dictionary is not empty bananas are yellow dragonfruit are red Can't find fig Can't find elderberry {banana => yellow, cantaloupe => orange, dragonfruit => red, apple => red}

Maps2.pl

#!/usr/bin/env perl
use utf8;
use Utils;
use strict;
use warnings;

MAIN:
{
	my $planet_diameters = {
		"Mercury" => 4879,
		"Venus" => 12103,
		"Earth" => 12756,
		"Mars" => 6794,
		"Jupiter" => 142985,
		"Saturn" => 120534,
		"Uranus" => 51115,
		"Neptune" => 49534,
		"Pluto" => 2374,
		"Ceres" => 946,
		"Eris" => 2326,
		"Makemake" => 1430
	};

	foreach my $planet (keys(%$planet_diameters)) {
		print $planet, " has a diameter of ", $planet_diameters->{$planet}, " km\n";
	}
}

Output

$ perl Maps2.pl Mars has a diameter of 6794 km Saturn has a diameter of 120534 km Uranus has a diameter of 51115 km Ceres has a diameter of 946 km Mercury has a diameter of 4879 km Makemake has a diameter of 1430 km Pluto has a diameter of 2374 km Jupiter has a diameter of 142985 km Venus has a diameter of 12103 km Earth has a diameter of 12756 km Neptune has a diameter of 49534 km Eris has a diameter of 2326 km

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References

[[Perl Language Reference]]
[[Comprehensive Perl Archive Network (CPAN)]]
[[Beginning Perl]], Simon Cozens
[[Perl Monks Tutorials]]