# FreeBSD Manual Pages

```Algorithm::CheckDigitsUser7Contributed Perl Algorithm::CheckDigits::M07_001(3)

NAME
CheckDigits::M07_001 - compute check digits modulo 7 method 1

SYNOPSIS
use Algorithm::CheckDigits;

\$m001 = CheckDigits('m001');

if (\$m001->is_valid('1234567892')) {
# do something
}

\$cn = \$m001->complete('123456789');	# \$cn =	'1234567892'

\$cd = \$m001->checkdigit('1234567892');	# \$cd =	'2'

\$bn = \$m001->basenumber('1234567892');	# \$bn =	'123456789'

DESCRIPTION
ALGORITHM

2.  All digits at even positions	are added.

3.  The sum of step 1 and 2 is taken modulo 7.

4.  This	is the check digit.

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 undef if \$number
does	not consist solely of digits.

basenumber(\$number)
Returns the basenumber of \$number if	\$number	has a valid check
digit.

Return undef	otherwise.

checkdigit(\$number)
Returns the check digit belonging to	\$number	or undef if \$number
does	not consist solely of digits.

EXPORT
None by default.

AUTHOR
Mathias Weidner,	"<mamawe@cpan.org>"