---
name: "Algorithm::CheckDigits::M10_003"
section: "3pm"
platform: "linux"
package: "libalgorithm-checkdigits-perl"
version: "1.3.6-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Algorithm::CheckDigits::M10_003"
---

# Algorithm::CheckDigits::M10\_003(3pm)

compute check digits for ISMN

## NAME

CheckDigits::M10\_003 - compute check digits for ISMN

## SYNOPSIS

```
  use Algorithm::CheckDigits;
  $ismn = CheckDigits('ismn');
  if ($ismn->is_valid('M-345-24680-5')) {
        # do something
  }
  $cn = $ismn->complete('M-345-24680');
  # $cn = 'M-345-24680-5'
  $cd = $ismn->checkdigit('M-345-24680-5');
  # $cd = '5'
  $bn = $ismn->basenumber('M-345-24680-5');
  # $bn = 'M-345-24680'
```

## DESCRIPTION

### ALGORITHM

- 1\.

  The 'M' as the first number gets the value 3. Beginning left all numbers are weighted alternatively 3 and 1.

- 2\.

  The sum of all products is computed.

- 3\.

  The sum of step 3 ist taken modulo 10.

- 4\.

  The check digit is the difference between 10 and the number from step 3 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, `"<mamawe@cpan.org>"`

## SEE ALSO

perl, CheckDigits, *www.pruefziffernberechnung.de*.