#!/usr/bin/perl -w
#
# Union, Intersection, and Difference between two arrays
#
# 03.15.2001
# A quick little hack based on information contained in 
# this node:
# http://perlmonks.org/index.pl?node_id=5733
#
# As an example of testing two array's equality
#
# This is taken directly out of the faq here:
# http://language.perl.com/newdocs/pod/perlfaq4.html#How_do_I_test_whe
+ther_two_arrays
#
#
#
use strict;
use Data::Dumper;
 
my @a1 = ("CUSTORDS.DAT",
        "RECEIPTS.DAT");
 
print "Array 1:\n";
print Dumper(@a1),"\n";

my @b1 = ("CUSTORDS.DAT",
        "ONHAND.DAT",
        "RECEIPTS.DAT");
print "Array 2:\n";
print Dumper(@b1),"\n";

my @union = my @inter = my @diff = ();
my %count = ();

foreach my $element (@a1, @b1) {
        $count{$element}++;
};
foreach my $element (keys %count) {
        push @union, $element;
        push @{ $count{$element} > 1 ? \@inter : \@diff }, $element;
};

print "Count:\n";
print Dumper(%count),"\n";
print "Union:\n";
print Dumper(@union),"\n";
print "Intersection:\n";
print Dumper(@inter),"\n";
print "Difference:\n";
print Dumper(@diff),"\n";
[download]

Array 1:
$VAR1 = 'CUSTORDS.DAT';
$VAR2 = 'RECEIPTS.DAT';

Array 2:
$VAR1 = 'CUSTORDS.DAT';
$VAR2 = 'ONHAND.DAT';
$VAR3 = 'RECEIPTS.DAT';

Count:
$VAR1 = 'ONHAND.DAT';
$VAR2 = '1';
$VAR3 = 'RECEIPTS.DAT';
$VAR4 = '2';
$VAR5 = 'CUSTORDS.DAT';
$VAR6 = '2';

Union:
$VAR1 = 'ONHAND.DAT';
$VAR2 = 'RECEIPTS.DAT';
$VAR3 = 'CUSTORDS.DAT';

Intersection:
$VAR1 = 'RECEIPTS.DAT';
$VAR2 = 'CUSTORDS.DAT';
 
Difference:
$VAR1 = 'ONHAND.DAT';
[download]