Adds support for cnpj alphanumeric values

[charllysonsouza]

Description

Recently, the official Brazilian government decreed a new rule requiring that the CNPJ include not only digits, but also capital letters. This rule will come into effect in July 2026. At this time, most of systems are adapting. It would be interesting if we could generate a cnpj in this new format. I've tried to open a pull request with this feature, but without succeeded.

LINQPad Code Example

public static class ExtensionsForBrazil
{
   private static readonly int[] CnpjFirstDigitWeights = [5,4,3,2,9,8,7,6,5,4,3,2];
   private static readonly int[] CnpjSecondDigitWeights = [6,5,4,3,2,9,8,7,6,5,4,3,2];
   private const string AlphaNumericChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
   private const string NumericChars = "0123456789";

   /// <summary>
   /// Cadastro Nacional da Pessoa Jurídica
   /// </summary>
   /// <param name="includeFormatSymbols">Includes formatting symbols.</param>
   public static string Cnpj(this Company c, bool includeFormatSymbols = true, bool includeOnlyDigits = false, bool includeOnlyAlphaNumerics = false)
   {
      string chars;

      if (includeOnlyDigits)
         chars = NumericChars;
      else if (includeOnlyAlphaNumerics)
         chars = AlphaNumericChars;
      else
         chars = c.Random.Bool() ? NumericChars : AlphaNumericChars;

      var cnpj = "";
      for (var i = 0; i < 8; i++)
         cnpj += chars[c.Random.Int(0, chars.Length - 1)];

      cnpj += "0001";

      var firstDigit = CalculateDigit(cnpj, CnpjFirstDigitWeights);
      cnpj += firstDigit;

      var secondDigit = CalculateDigit(cnpj, CnpjSecondDigitWeights);
      cnpj += secondDigit;

      if ( includeFormatSymbols )
         cnpj = $"{cnpj[0]}{cnpj[1]}.{cnpj[2]}{cnpj[3]}{cnpj[4]}.{cnpj[5]}{cnpj[6]}{cnpj[7]}/{cnpj[8]}{cnpj[9]}{cnpj[10]}{cnpj[11]}-{cnpj[12]}{cnpj[13]}";

      return cnpj;
   }

   private static int CalculateDigit(string cnpj, int[] weights)
   {
      var sum = cnpj.Select((value, i) => (value - '0') * weights[i]).Sum();
      var remainder = sum % 11;
      return remainder < 2 ? 0 : 11 - remainder;
   }
}

What alternatives have you considered?

n/a

Could you help with a pull-request?

Yes

[Sussumu]

This would be great! I assume a lot of devs are now implementing those changes as we are getting close to the deadline of this new Cnpj type.

With the implementation shown there could be some confusion between the includeOnlyDigits and includeOnlyAlphaNumerics since they are mutually exclusive. Maybe just one allowAlphanumerics is enough. However I'd like to be able to "force" the generator to include at least one letter to properly test the new type. But there needs to be some calculation to make this possible. We could generate them at random until we get one letter (slow, may take a while) or change the calculation to always include a letter (may not be possible, though probably is). We could also set a letter in a particular position but I think this defeats the purpose of having a method to generate Cnpj in the first place.