Algorithm::CheckDigits::MXX_001 (3pm)

  use Algorithm::CheckDigits;

  $pa = CheckDigits('pa_de');

  if ($pa->is_valid('2406055684D<<6810203<0705109<6')) {
        # do something
  }

  $cn = $pa->complete('240605568_D<<681020_<070510_<_');
  # $cn = '2406055684D<<6810203<0705109<6'

  $cd = $pa->checkdigit('2406055684D<<6810203<0705109<6');
  # $cd = '6'

  $bn = $pa->basenumber('2406055684D<<6810203<0705109<6');
  # $bn = '240605568_D<<681020_<070510_<_'

\s-1ALGORITHM\s0

1.

Beginning left all digits are weighted with 7,3,1,7,3,1,...

2.

The sum of those products is computed.

3.

The checksum is the last digit of the sum from step 2 (modulo 10).

4.

Step 1 to 3 is performed for every part of the number and for all 3 parts including the particular checkdigit to compute the total checksum.

\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 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.

\s-1EXPORT\s0

None by default.

Mathias Weidner, <[email protected]>

Aaron W. West pointed me to a fault in the computing of the check digit.

perl, CheckDigits, www.pruefziffernberechnung.de, www.export911.com/e911/coding/upcChar.htm, www.adams1.com/pub/russadam/upccode.html, http://www.upcdatabase.com.