Mathias Weidner > Algorithm-CheckDigits-v1.3.0 > Algorithm::CheckDigits::MXX_005

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Module Version: 0.53   Source   Latest Release: Algorithm-CheckDigits-v1.3.2

# NAME

CheckDigits::MXX_005 - compute check digits for ESR9 (CH)

# SYNOPSIS

```  use Algorithm::CheckDigits;

\$esr = CheckDigits('esr9');

if (\$esr->is_valid('123456786')) {
# do something
}

\$cn = \$esr->complete('12345678');
# \$cn = '123456786'

\$cd = \$esr->checkdigit('123456786');
# \$cd = '6'

\$bn = \$esr->basenumber('123456786');
# \$bn = '12345678'```

# DESCRIPTION

## ALGORITHM

1. Digits are processed left to right. For the first digit applies the balance is 0.
2. The new balance is taken from the balance table according to the current balance (row) and the digit (column).
3. The check digit is the difference from the last balance to 10 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>`