NAME

CheckDigits::MXX_006 - compute check digits with Verhoeff scheme

SYNOPSIS

  use Algorithm::CheckDigits;

  $verhoeff = CheckDigits('verhoeff');

  if ($verhoeff->is_valid('14567894')) {
	# do something
  }

  $cn = $verhoeff->complete('1456789');
  # $cn = '14567894'

  $cd = $verhoeff->checkdigit('14567894');
  # $cd = '4'

  $bn = $verhoeff->basenumber('14567894');
  # $bn = '1456789'
  

DESCRIPTION

ALGORITHM

1. Right to left 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.

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

Jonathan Peters wrote Algorithm::Verhoeff from which I took the routine to compute the checkdigits.

SEE ALSO

perl, CheckDigits, http://www.cs.utsa.edu/~wagner/laws/verhoeff.html, http://www.cs.nmsu.edu/~cssem/Dickcheckdoc.pdf