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 diëder 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 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

SEE ALSO

perl, CheckDigits, www.pruefziffernberechnung.de,