package Algorithm::CheckDigits::MBase_001;
use 5.006;
use strict;
use warnings;
use integer;
our $VERSION = '0.53';
our @ISA = qw(Algorithm::CheckDigits);
sub new {
my $proto = shift;
my $type = shift;
my $class = ref($proto) || $proto;
my $self = bless({}, $class);
$self->{type} = lc($type);
return $self;
} # new()
sub is_valid {
my ($self,$number) = @_;
if ($number =~ /^(\d+)(\d)$/) {
return $2 == $self->_compute_checkdigit($1);
}
return ''
} # is_valid()
sub complete {
my ($self,$number) = @_;
if ($number =~ /^\d+$/) {
return $number . $self->_compute_checkdigit($number);
}
return '';
} # complete()
sub basenumber {
my ($self,$number) = @_;
if ($number =~ /^(\d+)(\d)$/) {
return $1 if ($2 == $self->_compute_checkdigit($1));
}
return '';
} # basenumber()
sub checkdigit {
my ($self,$number) = @_;
if ($number =~ /^(\d+)(\d)$/) {
return $2 if ($2 == $self->_compute_checkdigit($1));
}
return '';
} # checkdigit()
sub _compute_checkdigit {
my $self = shift;
my $number = shift;
if ($number =~ /^\d+$/) {
my @digits = split(//,$number);
my $sum = 0;
my $even = 0;
for (my $i = 0; $i <= $#digits; $i++) {
if ($even) {
$sum += $digits[$i];
} else {
$sum += 3 * $digits[$i];
}
$even = not $even;
}
return (10 - ($sum % 10)) % 10;
}
return -1;
} # _compute_checkdigit()
# Preloaded methods go here.
1;
__END__
=head1 NAME
CheckDigits::MBase_001 - compute check digits for UPC (US)
=head1 SYNOPSIS
use Algorithm::CheckDigits;
$rv = CheckDigits('upc');
if ($rv->is_valid('012345678905')) {
# do something
}
$cn = $rv->complete('01234567890');
# $cn = '012345678905'
$cd = $rv->checkdigit('012345678905');
# $cd = '5'
$bn = $rv->basenumber('012345678905');
# $bn = '01234567890'
=head1 DESCRIPTION
=head2 ALGORITHM
=over 4
=item 1
Add all digits in odd-numbered positions.
=item 2
Multiply the sum from step 1 with 3.
=item 3
Add all digits in even-numbered positions.
=item 4
Add the product from step 2 and the sum from step 3.
=item 5
If the sum from step 4 is 0 modulo 10, the check digit is 0. Else the
check digit is 10 minus the sum from step 4 taken modulo 10.
=back
=head2 METHODS
=over 4
=item is_valid($number)
Returns true only if C<$number> consists solely of numbers and the last digit
is a valid check digit according to the algorithm given above.
Returns false otherwise,
=item complete($number)
The check digit for C<$number> is computed and concatenated to the end
of C<$number>.
Returns the complete number with check digit or '' if C<$number>
does not consist solely of digits and spaces.
=item basenumber($number)
Returns the basenumber of C<$number> if C<$number> has a valid check
digit.
Return '' otherwise.
=item checkdigit($number)
Returns the checkdigit of C<$number> if C<$number> has a valid check
digit.
Return '' otherwise.
=back
=head2 EXPORT
None by default.
=head1 AUTHOR
Mathias Weidner, C<< <mamawe@cpan.org> >>
=head1 THANKS
Aaron W. West pointed me to a fault in the computing of the check
digit.
=head1 SEE ALSO
L<perl>,
L<CheckDigits>,
F<www.pruefziffernberechnung.de>,
F<www.export911.com/e911/coding/upcChar.htm>,
F<www.adams1.com/pub/russadam/upccode.html>,
F<http://www.upcdatabase.com>.
=cut