Algorithm::CheckDigits::MXX_006 (3pm)

  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'

\s-1ALGORITHM\s0

1.

Right to left all digits are permutated according to a permutation table.

2.

The permutated digits are combined using a die\*:der 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 die\*:der 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.

\s-1METHODS\s0

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.

\s-1EXPORT\s0

None by default.

Mathias Weidner, <[email protected]>

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

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