 CheckDigits::M11_017(3) compute check digits for EC-No, EINECS, ELINCS

## SYNOPSIS

use Algorithm::CheckDigits;
\$ecno = CheckDigits('ecno');
if (\$ecno->is_valid('200-236-6')) {
# do something
}
\$cn = \$ecno->complete('200-236-');
# \$cn = '200-236-6'
\$cd = \$ecno->checkdigit('200-236-6');
# \$cd = '6'
\$bn = \$ecno->basenumber('200-236-6');
# \$bn = '200-236-'

## ALGORITHM

1.
From left to right all digits are multiplied with their position in the sequence.
2.
3.
The sum of step 2 is taken modulo 11.

The checkdigit is the last digit of the result.

## 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, <[email protected]>