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# NAME

CheckDigits::M97_002 - compute check digits for International Bank Account Number (IBAN)

# SYNOPSIS

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

\$iban = CheckDigits('iban');

if (\$iban->is_valid('DE88 2008 0000 09703 7570 0')) {
# do something
}

\$cn = \$iban->complete('DE00 2008 0000 09703 7570 0');
# \$cn = 'DE88 2008 0000 09703 7570 0'

\$cd = \$iban->checkdigit('DE88 2008 0000 09703 7570 0');
# \$cd = '88'

\$bn = \$iban->basenumber('DE88 2008 0000 09703 7570 0');
# \$bn = 'DE00 2008 0000 09703 7570 0'
``````

# DESCRIPTION

## ALGORITHM

0

The IBAN number must be prepared. The first two letters and the checksum will be moved to the right end. The letters are substituted according to the substitute table and the checksum is set to '00'.

1

The whole number is taken modulo 97.

2

The checksum is difference between 98 and the result of step 1.

3

If the checksum is smaller then 10, a leading zero will be prepended.

## 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 checkdigits of `\$number` if `\$number` has a valid check digit.

Return '' otherwise.

None by default.

# AUTHOR

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

# THANKS

Detlef Pilzecker pointed out to me that there may be more letters as the first two in an IBAN number. He also made me aware of a faster method to compute the check number than using Math::BigInt.

# SEE ALSO

perl, CheckDigits, www.pruefziffernberechnung.de, www.sic.ch/en/tkicch_home/tkicch_standardization/tkicch_financialinstitutions_ibanipi.htm.