Mathias Weidner > Algorithm-CheckDigits-v1.3.0 > Algorithm::CheckDigits::MXX_003

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Module Version: v1.2.1   Source   Latest Release: Algorithm-CheckDigits-v1.3.2

# NAME

CheckDigits::MXX_003 - compute check digits for DEM

# SYNOPSIS

```  use Algorithm::CheckDigits;

\$dem = CheckDigits('dem');

if (\$dem->is_valid('GD0645027K1')) {
# do something
}

\$cn = \$dem->complete('GD0645027K');
# \$cn = 'GD0645027K1'

\$cd = \$dem->checkdigit('GD0645027K1');
# \$cd = '1'

\$bn = \$dem->basenumber('GD0645027K1');
# \$bn = 'GD0645027K'```

# DESCRIPTION

## ALGORITHM

The algorithm is a variation of the Verhoeff scheme.

0

All letters are changed to numbers.

1

All digits are permutated according to a permutation table.

2

The permutated digits are combined using a diëder table. The first with the second, the result with the third, this result with the fourth and so on.

3

The result of the last combination in the diëder table is in such a way combined that the result is 0 (zero). The number used for this combination is the checksum.

For details look at the source.

## 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>`

# SEE ALSO

perl, CheckDigits, www.pruefziffernberechnung.de,

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