NAME

CheckDigits::MXX_003 - compute check digits for DEM

SYNOPSIS

  use Algorithm::CheckDigits;
  $dem = CheckDigits('dem');
  if ($dem->is_valid('GD0645027K1')) {
        # do something
  }
  $cn = $dem->complete('GD0645027K');
  # $cn = 'GD0645027K1'
  $cd = $dem->checkdigit('GD0645027K1');
  # $cd = '1'
  $bn = $dem->basenumber('GD0645027K1');
  # $bn = 'GD0645027K'

DESCRIPTION

ALGORITHM

The algorithm is a variation of the Verhoeff scheme.

0: All letters are changed to numbers.
1: All digits are permutated according to a permutation table.
2: The permutated digits are combined using a dieeder table. The first with the second, the result with the third, this result with the fourth and so on.
3: The result of the last combination in the dieeder 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>