Algorithm::CheckDigits::MBase_001(3)

NAME
CheckDigits::MBase_001 - compute check digits for UPC (US)

SYNOPSIS
  use Algorithm::CheckDigits;

  $rv = CheckDigits('upc');

  if ($rv->is_valid('012345678905')) {
        # do something
  }

  $cn = $rv->complete('01234567890');
  # $cn = '012345678905'

  $cd = $rv->checkdigit('012345678905');
  # $cd = '5'

  $bn = $rv->basenumber('012345678905');
  # $bn = '01234567890'

DESCRIPTION

  ALGORITHM

1.  Add all digits in odd-numbered positions.

2.  Multiply the sum from step 1 with 3.

3.  Add all digits in even-numbered positions.

4.  Add the product from step 2 and the sum from step 3.

5.  If the sum from step 4 is 0 modulo 10, the check digit is 0. Else the check digit is 10 minus the sum from step 4 taken modulo 10.

  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, "<mamawe@cpan.org>"

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

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