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.\" ========================================================================
.\"
.IX Title "CheckDigits::M23_002 3pm"
.TH CheckDigits::M23_002 3pm "2008-05-17" "perl v5.10.0" "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::M23_002 \- compute check digits for VAT Registration Number (IE)
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Algorithm::CheckDigits;
\&
\&  $dni = CheckDigits(\*(Aqustid_ie\*(Aq);
\&
\&  if ($dni\->is_valid(\*(Aq8473625E\*(Aq)) {
\&        # do something
\&  }
\&
\&  $cn = $dni\->complete(\*(Aq8473625\*(Aq);
\&  # $cn = \*(Aq8473625E\*(Aq
\&
\&  $cd = $dni\->checkdigit(\*(Aq8473625E\*(Aq);
\&  # $cd = \*(AqE\*(Aq
\&
\&  $bn = $dni\->basenumber(\*(Aq8473625E\*(Aq);
\&  # $bn = \*(Aq8473625\*(Aq
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
.SS "\s-1ALGORITHM\s0"
.IX Subsection "ALGORITHM"
.IP "1." 4
Beginning right all digits are weighted with their position in the
number (i.e. the number left from the check digit is multiplied with
2, the next with 3 and so on).
.IP "2." 4
All products are added.
.IP "3." 4
The check digit is the sum from step 2 modulo 23. This number is
expressed as the corresponding letter from the alphabet where A\-V
correspond to 1\-22 and W stands for check digit 0.
.SS "\s-1METHODS\s0"
.IX Subsection "METHODS"
.IP "is_valid($number)" 4
.IX Item "is_valid($number)"
Returns true only if \f(CW$number\fR consists solely of numbers 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$number\fR
does not consist solely of digits and spaces.
.IP "basenumber($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 "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.