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.\" ========================================================================
.\"
.IX Title "CheckDigits::M10_004 3pm"
.TH CheckDigits::M10_004 3pm "2021-01-03" "perl v5.32.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
CheckDigits::M10_004 \- compute check digits for 2aus5, EAN, ILN, ISBN13, NVE
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Algorithm::CheckDigits;
\&
\&  $ean = CheckDigits(\*(Aqean\*(Aq);
\&
\&  if ($ean\->is_valid(\*(Aq7622200004607\*(Aq)) {
\&        # do something
\&  }
\&
\&  $cn = $ean\->complete(\*(Aq762220000460\*(Aq);
\&  # $cn = \*(Aq7622200004607\*(Aq
\&
\&  $cd = $ean\->checkdigit(\*(Aq7622200004607\*(Aq);
\&  # $cd = \*(Aq7\*(Aq
\&
\&  $bn = $ean\->basenumber(\*(Aq7622200004607\*(Aq);
\&  # $bn = \*(Aq762220000460\*(Aq
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
.SS "\s-1ALGORITHM\s0"
.IX Subsection "ALGORITHM"
.IP "1." 4
Beginning right all numbers are weighted alternatively 1 and 3 (that
is the check digit is weighted 1).
.IP "2." 4
The sum of all products is computed.
.IP "3." 4
The sum of step 3 ist taken modulo 10.
.IP "4." 4
The check digit is the difference between 10 and the number from step 3.
.PP
To validate the total of the digits of all numbers inclusive check
digit taken modulo 10 must be 0.
.SS "\s-1METHODS\s0"
.IX Subsection "METHODS"
.IP "is_valid($number)" 4
.IX Item "is_valid($number)"
Returns true only if \f(CW$number\fR consists solely of digits, spaces and hyphen
and the last digit is a valid check digit according to the algorithm given
above.
.Sp
Returns false otherwise,
.IP "complete($number)" 4
.IX Item "complete($number)"
The check digit for \f(CW$number\fR is computed and concatenated to the end
of \f(CW$number\fR.
.Sp
Returns the complete number with check digit or '' if \f(CW$number\fR
does not consist solely of digits, spaces and hyphen.
.IP "basenumber($number)" 4
.IX Item "basenumber($number)"
Returns the basenumber of \f(CW$number\fR if \f(CW$number\fR has a valid check
digit.
.Sp
Return '' otherwise.
.IP "checkdigit($number)" 4
.IX Item "checkdigit($number)"
Returns the checkdigit of \f(CW$number\fR if \f(CW$number\fR has a valid check
digit.
.Sp
Return '' otherwise.
.SS "\s-1EXPORT\s0"
.IX Subsection "EXPORT"
None by default.
.SH "BUGS AND LIMITATIONS"
.IX Header "BUGS AND LIMITATIONS"
When invoked as \f(CW\*(C`CheckDigits(\*(Aqisbn13\*(Aq)\*(C'\fR the module checks whether the first
three digits (the country code) are 978 or 979, the current (as of 2006) \s-1EAN\s0
country codes for books. If at any time other \s-1EAN\s0 country codes for \s-1ISBN\-13\s0
will be specified and the then responsible maintainer ignores this in the
code, please send a friendly email.
.SH "AUTHOR"
.IX Header "AUTHOR"
Mathias Weidner, <mathias@weidner.in\-bad\-schmiedeberg.de>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
perl,
CheckDigits,
\&\fIwww.pruefziffernberechnung.de\fR.