NAME

CheckDigits::MXX_002 - compute check digits for CAS

SYNOPSIS

  use Algorithm::CheckDigits;
  $cas = CheckDigits('cas');
  if ($cas->is_valid('1333-74-0')) {
        # do something
  }
  $cn = $cas->complete('1333-74-');
  # $cn = '1333-74-0'
  $cd = $cas->checkdigit('1333-74-0');
  # $cd = '0'
  $bn = $cas->basenumber('1333-74-0');
  # $bn = '1333-74-'

DESCRIPTION

ALGORITHM

1.: Beginning right with the second digit all digits are weighted ascending starting with 1.
2.: The sum of those products is computed.
3.: The checksum is the last digit of the sum from step 2 (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.

HERMIER Christophe made me aware that CAS is now assigning 10-digit CAS Registry Numbers (http://www.cas.org/newsevents/10digitrn.html)