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, <mathias@weidner.in-bad-schmiedeberg.de>

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.