CheckDigits::M11_009 - compute check digits NRIC (SG)

       Mathias Weidner, "<mamawe@cpan.org>"

ALGORITHM
       1.  Beginning left every digit is weighted with 2, 7, 6, 5, 4, 3, 2

       2.  The weighted digits are added.

       3.  The sum from step 2 is taken modulo 11.

       4.  The  checkdigit  is  11 minus the sum from step 3 converted to a character according to the following
           table:

             @cd = ('','A','B','C','D','E','F','G','H','I','Z','J', );

   METHODS
       is_valid($number)
           Returns true only if $number consists of seven digits (optional preceded by a letter out of 'F', 'G',
           'S', 'T') followed by a valid letter according to the algorithm given above.

           Returns false otherwise,

       complete($number)
           The check letter for $number is computed and appended to the end of $number.

           Returns the complete number with check digit or '' if $number does not consist solely of  digits  and
           letters.

       basenumber($number)
           Returns the basenumber of $number if $number has a valid check digit.

           Return '' otherwise.

       checkdigit($number)
           Returns '' if $number is valid.

           Return undef otherwise.

   EXPORT
       None by default.

       CheckDigits::M11_009 - compute check digits NRIC (SG)

       perl, CheckDigits, www.pruefziffernberechnung.de,

perl v5.36.0                                       2022-10-13               Algorithm::CheckDigits::M11_009(3pm)

         use Algorithm::CheckDigits;

         $nric = CheckDigits('nric_sg');

         if ($nric->is_valid('S1234567D')) {
               # do something
         }

         $cn = $nric->complete('S1234567');
         # $cn = 'S1234567D'

         $cd = $nric->checkdigit('S1234567D');
         # $cd = 'D'

         $bn = $nric->basenumber('S1234567D');
         # $bn = 'S1234567';