Algorithm::CheckDigits::M10_010 (3pm)

  use Algorithm::CheckDigits;

  $pck = CheckDigits('postcheckkonti');

  if ($pck->is_valid('85-12345678-7')) {
        # do something
  }

  $cn = $pck->complete('85-12345678');
  # $cn = '85-12345678-7'

  $cd = $pck->checkdigit('85-12345678-7');
  # $cd = '7'

  $bn = $pck->basenumber('85-12345678-7');
  # $bn = '85-12345678'

\s-1ALGORITHM\s0

1.

The sequence of digits is processed left to right. For the first digit we assume a carry forward of 0.

2.

For each digit d(i) the carry forward cf(i) is the digit at the the position p in the sequence ( 0, 9, 4, 6, 8, 2, 7, 1, 3, 5 ), where p is (d(i) + cf(i-1)) modulo 10.

3.

The check digit is the difference of the sum from step 3 to the next multiple of 10.

\s-1METHODS\s0

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.

\s-1EXPORT\s0

None by default.

Mathias Weidner, <[email protected]>

perl, CheckDigits, www.pruefziffernberechnung.de.