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Mathias Weidner > Algorithm-CheckDigits > Algorithm::CheckDigits::MBase_001

Algorithm-CheckDigits-v1.3.2.tar.gz

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Module Version: v1.3.2

# NAME

CheckDigits::MBase_001 - compute check digits for UPC (US)

# SYNOPSIS

```  use Algorithm::CheckDigits;

\$rv = CheckDigits('upc');

if (\$rv->is_valid('012345678905')) {
# do something
}

\$cn = \$rv->complete('01234567890');
# \$cn = '012345678905'

\$cd = \$rv->checkdigit('012345678905');
# \$cd = '5'

\$bn = \$rv->basenumber('012345678905');
# \$bn = '01234567890'```

# DESCRIPTION

## ALGORITHM

1. Add all digits in odd-numbered positions.
2. Multiply the sum from step 1 with 3.
3. Add all digits in even-numbered positions.
4. Add the product from step 2 and the sum from step 3.
5. If the sum from step 4 is 0 modulo 10, the check digit is 0. Else the check digit is 10 minus the sum from step 4 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.

None by default.

# AUTHOR

Mathias Weidner, `<mamawe@cpan.org>`

# THANKS

Aaron W. West pointed me to a fault in the computing of the check digit.