NAME

       CheckDigits::M11_015 - compute check digits for ESR5 (CH)

SYNOPSIS

         use Algorithm::CheckDigits;

         $ustid = CheckDigits('esr5_ch');

         if ($ustid->is_valid('123456786')) {
               # do something
         }

         $cn = $ustid->complete('12345678');
         # $cn = '123456786'

         $cd = $ustid->checkdigit('123456786');
         # $cd = '6'

         $bn = $ustid->basenumber('123456786');
         # $bn = '12345678';

DESCRIPTION

   ALGORITHM
       1.  Beginning left every digit is weighted with 7,9,10,5,8,4,2.

       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. Is the difference 10, the number won't
           be taken. If the difference is 11, the checkdigit is 0.

   METHODS
       is_valid($number)
           Returns true only if $number consists solely of numbers and hyphens and the two digits
           in the middle are valid check digits according to the algorithm given above.

           Returns false otherwise,

       complete($number)
           The check digit for $number is computed and inserted into the middle of $number.

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

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

           Return '' otherwise.

       checkdigit($number)
           Returns the check digits of $number if $number has valid check digits.

           Return '' otherwise.

   EXPORT
       None by default.

AUTHOR

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

SEE ALSO

       perl, CheckDigits, www.pruefziffernberechnung.de,