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.