NAME

CheckDigits::M23_002 - compute check digits for VAT Registration Number (IE)

SYNOPSIS

  use Algorithm::CheckDigits;

  $dni = CheckDigits('ustid_ie');

  if ($dni->is_valid('8473625E')) {
        # do something
  }

  $cn = $dni->complete('8473625');
  # $cn = '8473625E'

  $cd = $dni->checkdigit('8473625E');
  # $cd = 'E'

  $bn = $dni->basenumber('8473625E');
  # $bn = '8473625'

DESCRIPTION

ALGORITHM

1. Beginning right all digits are weighted with their position in the number (i.e. the number left from the check digit is multiplied with 2, the next with 3 and so on).
2. All products are added.
3. The check digit is the sum from step 2 modulo 23. This number is expressed as the corresponding letter from the alphabet where A-V correspond to 1-22 and W stands for check digit 0.

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>

SEE ALSO

perl, CheckDigits, www.pruefziffernberechnung.de.