NAME

CheckDigits::M11_013 - compute check digits for VAT Registration Number (GR)

SYNOPSIS

  use Algorithm::CheckDigits;

  $ustid = CheckDigits('ustid_gr');

  if ($ustid->is_valid('123456783')) {
        # do something
  }

  $cn = $ustid->complete('12345678');
  # $cn = '123456783'

  $cd = $ustid->checkdigit('123456783');
  # $cd = '3'

  $bn = $ustid->basenumber('123456783');
  # $bn = '12345678';

DESCRIPTION

ALGORITHM

1.: Beginning right with the digit before the checkdigit all digits are weighted with 2 ** position. I. e. the last digit is multiplied with 2, the next with 4, then 8 and so on.
2.: The weighted digits are added.
3.: The sum from step 2 is taken modulo 11.
4.: If the sum from step 3 is greater than 9, the check sum is 0 else it is the sum itself.

METHODS

is_valid($number): Returns true only if $number consists solely of numbers and the rightmost digit is a valid check digit according to the algorithm given above.
Returns false otherwise,
complete($number): The check digit for $number is computed and appended 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 check digits of $number if $number has valid check digits.
Return '' otherwise.

EXPORT

None by default.

AUTHOR

Mathias Weidner, "<mamawe@cpan.org>"