Algorithm::CheckDigits::M10_004 (3pm)

  use Algorithm::CheckDigits;

  $ean = CheckDigits('ean');

  if ($ean->is_valid('7622200004607')) {
        # do something
  }

  $cn = $ean->complete('762220000460');
  # $cn = '7622200004607'

  $cd = $ean->checkdigit('7622200004607');
  # $cd = '7'

  $bn = $ean->basenumber('7622200004607');
  # $bn = '762220000460'

\s-1ALGORITHM\s0

1.

Beginning right all numbers are weighted alternatively 1 and 3 (that is the check digit is weighted 1).

2.

The sum of all products is computed.

3.

The sum of step 3 ist taken modulo 10.

4.

The check digit is the difference between 10 and the number from step 3.

To validate the total of the digits of all numbers inclusive check digit taken modulo 10 must be 0.

\s-1METHODS\s0

is_valid($number)

Returns true only if $number consists solely of digits, spaces and hyphen 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, spaces and hyphen.

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.

When invoked as \*(C`CheckDigits('isbn13')\*(C' the module checks whether the first three digits (the country code) are 978 or 979, the current (as of 2006) \s-1EAN\s0 country codes for books. If at any time other \s-1EAN\s0 country codes for \s-1ISBN-13\s0 will be specified and the then responsible maintainer ignores this in the code, please send a friendly email.

Mathias Weidner, <[email protected]>

perl, CheckDigits, www.pruefziffernberechnung.de.