Quick Navigator

 Search Site Miscellaneous Server Agreement Year 2038 Credits

# Manual Reference Pages  -  ALGORITHM::CHECKDIGITS::M23_002 (3)

.ds Aq ’

### NAME

CheckDigits::M23_002 - compute check digits for VAT Registration Number (IE)

### SYNOPSIS

```

use Algorithm::CheckDigits;

\$dni = CheckDigits(ustid_ie);

if (\$dni->is_valid(8473625E)) {
# do something
}

\$cn = \$dni->complete(8473625);
# \$cn = 8473625E

\$cd = \$dni->checkdigit(8473625E);
# \$cd = E

\$bn = \$dni->basenumber(8473625E);
# \$bn = 8473625

```

### DESCRIPTION

#### ALGORITHM

 1. Beginning right all digits are weighted with their position in the number (i.e. the number left from the check digit is multiplied with 2, the next with 3 and so on). 2. All products are added. 3. The check digit is the sum from step 2 modulo 23. This number is expressed as the corresponding letter from the alphabet where A-V correspond to 1-22 and W stands for check digit 0.

#### 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.

None by default.

### AUTHOR

Mathias Weidner, <mamawe@cpan.org>