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A PHP utility to calculate check digits on CPF (Brazilian Individual's Taxpayer ID).

PHP Support

Passing ✔	Passing ✔	Passing ✔	Passing ✔

Features

• ✅ Flexible input: Accepts string or array of strings
• ✅ Format agnostic: Automatically strips non-numeric characters from string input
• ✅ Auto-expansion: Multi-character strings in arrays are expanded to individual digits
• ✅ Lazy evaluation: Check digits are calculated only when accessed (via properties)
• ✅ Caching: Calculated values are cached for subsequent access
• ✅ Property-style API: first, second, both, cpf (via magic __get)
• ✅ Minimal dependencies: Only lacus/utils
• ✅ Error handling: Specific types for type, length, and invalid CPF scenarios (TypeError vs Exception semantics)

Installation

# using Composer
$ composer require lacus/cpf-dv

Quick Start

<?php

use Lacus\BrUtils\Cpf\CpfCheckDigits;

$checkDigits = new CpfCheckDigits('054496519');

$checkDigits->first;    // '1'
$checkDigits->second;   // '0'
$checkDigits->both;     // '10'
$checkDigits->cpf;      // '05449651910'

Usage

The main resource of this package is the class CpfCheckDigits. Through an instance, you access CPF check-digit information:

• __construct: new CpfCheckDigits(string|array $cpfInput) — 9–11 digits (formatting stripped from strings).
• first: First check digit (10th digit of the CPF). Lazy, cached.
• second: Second check digit (11th digit of the CPF). Lazy, cached.
• both: Both check digits concatenated as a string.
• cpf: The complete CPF as a string of 11 digits (9 base digits + 2 check digits).

Input formats

The CpfCheckDigits class accepts multiple input formats:

String input: plain digits or formatted CPF (e.g. 054.496.519-10). Non-numeric characters are automatically stripped. Use 9 digits (base only) or 11 digits (only the first 9 are used).

Array of strings: single-character strings or multi-character strings (expanded to individual digits), e.g. ['0','5','4','4','9','6','5','1','9'], ['054496519'], ['054','496','519'].

Errors & exceptions handling

This package uses TypeError vs Exception semantics: type errors indicate incorrect API use (e.g. wrong type); exceptions indicate invalid or ineligible data (e.g. invalid CPF). You can catch specific classes or use the abstract bases.

• CpfCheckDigitsTypeError (abstract) — base for type errors; extends PHP’s TypeError
• CpfCheckDigitsInputTypeError — input is not string or string[]
• CpfCheckDigitsException (abstract) — base for data/flow exceptions; extends Exception
• CpfCheckDigitsInputLengthException — sanitized length is not 9–11
• CpfCheckDigitsInputInvalidException — input ineligible (e.g. repeated digits like 111111111)

<?php

use Lacus\BrUtils\Cpf\CpfCheckDigits;
use Lacus\BrUtils\Cpf\Exceptions\CpfCheckDigitsException;
use Lacus\BrUtils\Cpf\Exceptions\CpfCheckDigitsInputInvalidException;
use Lacus\BrUtils\Cpf\Exceptions\CpfCheckDigitsInputLengthException;
use Lacus\BrUtils\Cpf\Exceptions\CpfCheckDigitsInputTypeError;

// Input type (e.g. integer not allowed)
try {
    new CpfCheckDigits(12345678901);
} catch (CpfCheckDigitsInputTypeError $e) {
    echo $e->getMessage();
}

// Length (must be 9–11 digits after sanitization)
try {
    new CpfCheckDigits('12345678');
} catch (CpfCheckDigitsInputLengthException $e) {
    echo $e->getMessage();
}

// Invalid (e.g. repeated digits)
try {
    new CpfCheckDigits(['999', '999', '999']);
} catch (CpfCheckDigitsInputInvalidException $e) {
    echo $e->getMessage();
}

// Any data exception from the package
try {
    // risky code
} catch (CpfCheckDigitsException $e) {
    // handle
}

Other available resources

• CPF_MIN_LENGTH: 9 — class constant CpfCheckDigits::CPF_MIN_LENGTH, and global Lacus\BrUtils\Cpf\CPF_MIN_LENGTH when the autoloaded cpf-dv.php file is loaded.
• CPF_MAX_LENGTH: 11 — class constant CpfCheckDigits::CPF_MAX_LENGTH, and global Lacus\BrUtils\Cpf\CPF_MAX_LENGTH when cpf-dv.php is loaded.

Calculation algorithm

The package calculates CPF check digits using the official Brazilian algorithm:

1. First check digit (10th position): digits 1–9 of the CPF base; weights 10, 9, 8, 7, 6, 5, 4, 3, 2 (from left to right); remainder = 11 - (sum(digit × weight) % 11); result is 0 if remainder > 9, otherwise remainder.
2. Second check digit (11th position): digits 1–9 + first check digit; weights 11, 10, 9, 8, 7, 6, 5, 4, 3, 2 (from left to right); same formula.

Contribution & Support

We welcome contributions! Please see our Contributing Guidelines for details. If you find this project helpful, please consider:

• ⭐ Starring the repository
• 🤝 Contributing to the codebase
• 💡 Suggesting new features
• 🐛 Reporting bugs

License

This project is licensed under the MIT License — see the LICENSE file for details.

Changelog

See CHANGELOG for a list of changes and version history.

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