• NAME
• SYNOPSIS
• ALGORITHM
• METHODS
• EXPORT
• AUTHOR
• THANKS
• SEE ALSO

NAME

CheckDigits::MXX_003 - compute check digits for DEM

SYNOPSIS

  use CheckDigits;

  $dem = CheckDigits('dem');

  if ($pa->is_valid('GD0645027K1')) {
        # do something
  }

  $cn = $dem->complete('GD0645027K');
  # $cn = 'GD0645027K1'

  $cd = $dem->checkdigit('GD0645027K1');
  # $cd = '1'

  $bn = $dem->basenumber('GD0645027K1');
  # $bn = 'GD0645027K'

=head1 DESCRIPTION

ALGORITHM

1. All letters are changed to numbers.

2. All digits are permutated according to a permutation table.

3. The permutated digits are combined using a diëder table. The first with the second, the result with the third, this result with the fourth and so on.

4. The result of the last combination in the diëder table is in such a way combined that the result is 0 (zero). The number used for this combination is the checksum.

For details look at the source.

METHODS

is_valid($number)

Returns true only if $number consists solely of numbers and the last digit is a valid check digit according to the algorithm given above.

Returns false otherwise,

complete($number)

The check digit for $number is computed and concatenated to the end of $number.

Returns the complete number with check digit or '' if $number does not consist solely of digits and spaces.

basenumber($number)

Returns the basenumber of $number if $number has a valid check digit.

Return '' otherwise.

checkdigit($number)

Returns the checkdigit of $number if $number has a valid check digit.

Return '' otherwise.

EXPORT

None by default.

AUTHOR

Mathias Weidner, <mathias@weidner.in-bad-schmiedeberg.de>

THANKS

Aaron W. West pointed me to a fault in the computing of the check digit.

SEE ALSO

the perl manpage, the CheckDigits manpage, www.pruefziffernberechnung.de, www.export911.com/e911/coding/upcChar.htm, www.adams1.com/pub/russadam/upccode.html, http://www.upcdatabase.com.