Validations

The CrispyWaffle.Validations namespace validates and normalizes a small set of personal data formats: Brazilian taxpayer documents (CPF for individuals, CNPJ for companies) and e-mail addresses. It also exposes the precompiled regular expressions the rest of the library uses for IP addresses, e-mail addresses and string cleanup.

Use it when you accept CPF, CNPJ or e-mail input and want a check-digit validation without a third-party library. For formatting and other pt-BR specific conversions (such as formatting a CPF or parsing a Brazilian phone number), see the pt-BR internationalization package.

How it works

CPF and CNPJ

The document methods are string extension methods on PersonalDataValidation. They all share the same steps:

1. Remove every character that is not 0–9, so formatted input such as 529.982.247-25 or 19.664.626/0001-20 is accepted.
2. Check the length: 11 digits for a CPF, 14 for a CNPJ. Otherwise throw InvalidDocumentException.
3. Reject input that contains 11 identical consecutive digits (11111111111, 00000000000000, and so on) by throwing InvalidDocumentException.
4. Compute the two check digits with the standard modulus-11 algorithm. For each digit, the weighted sum is divided by 11; a remainder below 2 gives 0, otherwise the digit is 11 - remainder. A CPF uses weights 10 down to 2 (then 11 down to 2); a CNPJ uses 5,4,3,2,9,8,7,6,5,4,3,2 (then 6,5,4,3,2,9,8,7,6,5,4,3,2).

IsValidBrazilianPersonDocument and IsValidBrazilianCorporateDocument then compare the computed digits with the end of the original string. So the IsValid... methods return false for a document with wrong check digits, but throw InvalidDocumentException for wrong length or repeated digits. Wrap them in a try/catch if you need a plain boolean.

Only numeric documents are supported. Letters are stripped in step 1, so an alphanumeric CNPJ fails the length check.

E-mail addresses

ValidateEmailAddress matches the input against NetworkValidations.EmailAddressPattern, an RFC 5322-style expression that also accepts Unicode letters. It also repairs two common typos:

• An address that ends with combr (case-insensitive) has combr replaced with com.br.
• An address that contains a comma has each comma replaced with a dot.

The method returns the original or repaired address, or throws InvalidEmailAddressException. The repaired address is not matched against the pattern again.

Getting started

using System;
using CrispyWaffle.Validations;

try
{
    var cpfOk = "229.706.190-08".IsValidBrazilianPersonDocument();   // true
    var cnpjOk = "19664626000120".IsValidBrazilianCorporateDocument(); // true
    var email = "nobody@example.combr".ValidateEmailAddress();       // "nobody@example.com.br"
}
catch (InvalidDocumentException ex)
{
    Console.WriteLine(ex.Message);
}
catch (InvalidEmailAddressException ex)
{
    Console.WriteLine(ex.Message);
}

Reference

PersonalDataValidation

public static class PersonalDataValidation — validation and check-digit calculation for CPF and CNPJ, and e-mail validation.

All document methods throw NullReferenceException for null input.

NetworkValidations

public static class NetworkValidations — precompiled regular expressions for network data. Both use a 5-second match timeout.

StringValidations

public static class StringValidations — precompiled regular expressions used by the string helpers in Extension methods. All use CultureInvariant | IgnoreCase and a 5-second timeout.

InvalidDocumentException

public class InvalidDocumentException : Exception — thrown by the CPF and CNPJ methods of PersonalDataValidation when the document has the wrong number of digits or is made of repeated digits. Marked [Serializable].

InvalidEmailAddressException

public class InvalidEmailAddressException : Exception — thrown by ValidateEmailAddress when the address is empty or cannot be matched or repaired. Marked [Serializable].

Examples

Validate a CPF as a boolean

The IsValid... methods throw for malformed input. This wrapper turns every failure into false.

using CrispyWaffle.Validations;

static bool IsCpf(string input)
{
    if (string.IsNullOrWhiteSpace(input))
    {
        return false;
    }

    try
    {
        return input.IsValidBrazilianPersonDocument();
    }
    catch (InvalidDocumentException)
    {
        return false;
    }
}

var a = IsCpf("135.117.490-85"); // true
var b = IsCpf("135.117.490-86"); // false: wrong check digit
var c = IsCpf("111.111.111-11"); // false: repeated digits

Compute check digits

using CrispyWaffle.Validations;

// The input must have 11 digits, but only the first 9 are used.
// Pad with two placeholder digits to complete a new CPF.
var digits = "22970619000".CalculateBrazilianPersonDocumentDigits(); // "08"
var cpf = "229706190" + digits;                                      // "22970619008"

Extract an IP address from a header

using CrispyWaffle.Validations;

var header = "for=203.0.113.7;proto=https";
var ip = NetworkValidations.IpAddressPattern.IsMatch(header)
    ? NetworkValidations.IpAddressPattern.Match(header).Value   // "203.0.113.7"
    : null;

See also

• pt-BR internationalization for formatting documents and other Brazilian conversions
• Extension methods for the string helpers that use these patterns
• Utilities