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package Algorithm::CheckDigits::M09_001;
use 5.006;
use strict;
use warnings;
our @ISA = qw(Algorithm::CheckDigits);
sub new {
my $proto = shift;
my $class = ref($proto) || $proto;
return bless({}, $class);
} # new()
sub is_valid {
my ($self,$number) = @_;
if ($number =~ /^([A-Za-z][0-9]{10})([0-9])$/) {
return $2 == _compute_checkdigit($1);
}
return 0;
} # is_valid()
sub complete {
my ($self,$number) = @_;
if ($number =~ /^[A-Za-z][0-9]{10}$/) {
return $number . _compute_checkdigit($number);
}
return '';
} # complete()
sub basenumber {
my ($self,$number) = @_;
if ($number =~ /^([A-Za-z][0-9]{10})([0-9])$/) {
return $1 if ($2 == _compute_checkdigit($1));
}
return '';
} # basenumber()
sub checkdigit {
my ($self,$number) = @_;
if ($number =~ /^([A-Za-z][0-9]{10})([0-9])$/) {
return $2 if ($2 == _compute_checkdigit($1));
}
return '';
} # checkdigit()
sub _compute_checkdigit {
my $number = shift;
if ($number =~ /^([A-Za-z])([0-9]{10})$/) {
my @nums = ();
my $sum = 0;
push(@nums,ord(uc($1)) - ord('A') +1);
push(@nums,split(//,$2));
foreach my $num (@nums) {
$sum += $num;
}
return 8 - ($sum % 9);
}
return -1;
} # _compute_checkdigit()
# Preloaded methods go here.
1;
__END__
=head1 NAME
CheckDigits::M09_001 - compute check digits for Euro notes
=head1 SYNOPSIS
use Algorithm::CheckDigits;
$euro = CheckDigits('euronote');
if ($euro->is_valid('X07738250357')) {
# do something
}
$cn = $euro->complete('X0773825035'); # $cn = 'X07738250357'
$cd = $euro->checkdigit('X07738250357'); # $cd = '7'
$bn = $euro->basenumber('X07738250357'); # $bn = 'X0773825035'
=head1 DESCRIPTION
=head2 ALGORITHM
=over 4
=item 1
Letters are replaced with their position in the alphabet ('A' = 1, ...).
=item 2
The total of the digits of all numbers is computed.
=item 3
This sum is taken modulo 9.
=item 4
The check digit is the difference between 8 and the number of step 3.
=back
To validate the last digit of the total of the digits of all numbers
inclusive check digit must be 8.
=head2 METHODS
=over 4
=item is_valid($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<$number>
does not consist solely of digits.
=item basenumber($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, E<lt>mathias@weidner.in-bad-schmiedeberg.deE<gt>
=head1 SEE ALSO
L<perl>,
L<CheckDigits>,
F<www.pruefziffernberechnung.de>.
=cut
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