NAME

       Business::BR::CNPJ - Perl module to test for correct CNPJ numbers

SYNOPSIS

         use Business::BR::CNPJ;

         print "ok " if test_cnpj('90.117.749/7654-80'); # prints 'ok '
         print "bad " unless test_cnpj('88.222.111/0001-10'); # prints 'bad '

DESCRIPTION

       The CNPJ number is an identification number of Brazilian companies emitted by the
       Brazilian Ministry of Revenue, which is called "Ministerio da Fazenda".

       CNPJ stands for "Cadastro Nacional de Pessoa Juridica" (literally, national juridical
       person registration) as opposed to the CPF number for natural persons. Sometime ago, it
       was called CGC ("Cadastro Geral de Contribuinte" or general taxpayer registration).

       The CNPJ is comprised of a base of 8 digits, a 4-digits radical and 2 check digits. It is
       usually written like '11.111.111/0001-55' so as to be more human-readable.

       This module provides "test_cnpj" for checking that a CNPJ number is correct. Here a
       correct CNPJ number means

       •   it is 14 digits long

       •   it satisfies the two check equations mentioned below

       Before checking, any non-digit letter is stripped, making it easy to test formatted
       entries like '11.111.111/0001-55' and entries with extra blanks like '   43.337.004 /
       0001-72  '.

       test_cnpj
             test_cnpj('48.999.764/0001-60') # incorrect CPF, returns 0
             test_cnpj(' 43.337.004/0001-72 ') # is ok, returns 1
             test_cnpj('888') # nope, returns undef

           Tests whether a CNPJ number is correct. Before testing, any non-digit character is
           stripped. Then it is expected to be 14 digits long and to satisfy two check equations
           which validate the last two check digits.  See "THE CHECK EQUATIONS".

           The policy to get rid of '.', '/' and '-' is very liberal.  It indeeds discards
           anything that is not a digit (0, 1, ..., 9) or letter. That is handy for discarding
           spaces as well.

             test_cnpj(' 66.818.021/0001-27 ') # is ok, returns 1

           But extraneous inputs like 'a53##045%4-20**0001!50' are also accepted. If you are
           worried about this kind of input, just check against a regex:

             warn "bad CNPJ: only digits (14) expected"
               unless ($cnpj =~ /^\d{14}$/);

             warn "bad CNPJ: does not match mask '__.___.___/____-__'"
               unless ($cnpj =~ /^\d{2}\.\d{3}\.\d{3}/\d{4}-\d{2}$/);

           NOTE. Integer numbers like 3337004000158 (or 3_337_004_0001_58) with fewer than 14
           digits will be normalized (eg. to 03_337_004_0001_58) before testing.

       canon_cnpj
             canon_cnpj(1); # returns '00000000000001'
             canon_cnpj('99.999.222/0001-12'); # returns '99999222000112'

           Canon's a candidate for a CNPJ number. In case, the argument is an integer, it is
           formatted to at least fourteen digits. Otherwise, it is stripped of any non-
           alphanumeric characters and returned as it is.

       format_cnpj
             format_cnpj('00 000 000 0000 00'); # returns '00.000.000/0000-00'

           Formats its input into '00.000.000/0000-00' mask.  First, the argument is canon'ed and
           then dots, slash and hyphen are added to the first 14 digits of the result.

       parse_cnpj
             ($base, $filial, $dv) = parse_cnpj($cpf);
             $hashref = parse_cnpj('11.222.333/4444-00'); # { base => '11222333', filial => '4444' dv => '00' }

           Splits a candidate for CNPJ number into base, radical and check digits (dv - digitos
           de verificaca~o). It canon's the argument before splitting it into 8-, 4- and 2-digits
           parts. In a list context, returns a three-element list with the base, the radical and
           the check digits. In a scalar context, returns a hash ref with keys 'base', 'filial'
           and 'dv' and associated values.

       random_cnpj
             $rand_cnpj = random_cnpj($valid);

             $good_cnpj = random_cnpj();
             $cnpj = random_cnpj(1); # also a good one
             $bad_cnpj = random_cnpj(0); # bad CNPJ

           Generates a random CNPJ. If $valid is omitted or 1, it is guaranteed to be correct. If
           $valid is 0, it is guaranteed to be incorrect.  This function is intented for mass
           test. (Use it wisely.)

           The implementation is: generate a 8-digits random number for the base, and the
           variation is chosen 95% of the time to be '0001' and the other 5% a skewed random
           distribution with the expression "int(sqr rand(1E8))" is used. A uniform distribution
           is expected from "rand". With the base and variation, the check digits are computed.
           If $valid==0, the check digits are computed not to satisfy the check equations.

   EXPORT
       "test_cnpj" is exported by default. "canon_cnpj", "format_cnpj", "parse_cnpj" and
       "random_cnpj" can be exported on demand.

THE CHECK EQUATIONS

       A correct CNPJ number has two check digits which are computed from the 12 first digits.
       Consider the CNPJ number written as 14 digits

         c[1] c[2] c[3] c[4] c[5] c[6] c[7] c[8] c[9] c[10] c[11] c[12] dv[1] dv[2]

       To check whether a CNPJ is correct or not, it has to satisfy the check equations:

         5*c[1]+4*c[2]+3*c[3]+2*c[4]+9*c[5]+
         8*c[6]+7*c[7]+6*c[8]+5*c[9]+4*c[10]+
                             3*c[11]+2*c[12]+dv[1] = 0 (mod 11) or
                                                   = 1 (mod 11) (if dv[1]=0)

       and

         6*c[1]+5*c[2]+4*c[3]+3*c[4]+2*c[5]+
         9*c[6]+8*c[7]+7*c[8]+6*c[9]+5*c[10]+
                     4*c[11]+3*c[12]+2*dv[1]+dv[2] = 0 (mod 11) or
                                                   = 1 (mod 11) (if dv[2]=0)

BUGS

       I heard that there are exceptions of CNPJ numbers which don't obey the check equations and
       are still authentic. I have never found one of them.

SEE ALSO

       To make sure this module works, one can try the results obtained against those found with
       "Emissa~o de Comprovante de Inscrica~o e de Situaca~o Cadastral de Pessoa Juridica", a web
       page which the Brazilian Ministry of Revenue provides for public consultation on
       regularity status of the taxpayer.  This page tells if the CNPJ number is a correct entry
       (14-digits-long with verified check digits), if it references a real company and if it is
       regular with the government body.

       Given a bad CNPJ, the after-submit page tells "O numero do CNPJ na~o e valido" (the CNPJ
       number is not valid).  If the CNPJ is a good one but does not reference a real company, it
       says "CNPJ na~o existe em nossa base de dados" (CNPJ does not exist in our database).
       Otherwise, it shows a details form for the identified taxpayer.

       Note that this module only tests correctness.  It doesn't enter the merit whether the CNPJ
       number actually exists at the Brazilian government databases.

       As you might have guessed, this is not the first Perl module to approach this kind of
       functionality. Take a look at

         http://search.cpan.org/search?module=Brasil::Checar::CGC

       Please reports bugs via CPAN RT, http://rt.cpan.org/NoAuth/Bugs.html?Dist=Business-BR-Ids
       By doing so, the author will receive your reports and patches, as well as the problem and
       solutions will be documented.

AUTHOR

       A. R. Ferreira, <ferreira@cpan.org>

COPYRIGHT AND LICENSE

       Copyright (C) 2005 by A. R. Ferreira

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of
       Perl 5 you may have available.