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# NAME

CheckDigits::M10_005 - compute check digits for Deutsche Post Identcode/Leitcode (DE)

# SYNOPSIS

``````  use Algorithm::CheckDigits;

\$ic = CheckDigits('identcode_dp');

if (\$ic->is_valid('21.802 580.906 6')) {
# do something
}

\$cn = \$ic->complete('21.802 580.906');
# \$cn = '21.802 580.9066'

\$cd = \$ic->checkdigit('21.802 580.906 6');
# \$cd = '6'

\$bn = \$ic->basenumber('21.802 580.906 6');
# \$bn = '21.802 580.906'
``````

# DESCRIPTION

## ALGORITHM

1. Beginning left all numbers are weighted alternatively 4 and 9.

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.

## 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>`