for testing and deploying your application
for finding and fixing issues
for empowering human code reviews
<?php
declare(strict_types = 1);
namespace byrokrat\checkdigit;
/**
* Modulo10 calculator
*/
class Modulo10 implements Calculator
{
use AssertionsTrait;
* Check if the last digit of number is a valid modulo 10 check digit
public function isValid(string $number): bool
return substr($number, -1) === $this->calculateCheckDigit(substr($number, 0, -1) ?: '');
}
* Calculate the modulo 10 check digit for number
public function calculateCheckDigit(string $number): string
$this->assertNumber($number);
$sum = $this->calculateSum($number);
$ceil = $sum;
while ($ceil % 10 != 0) {
$ceil++;
return (string)($ceil-$sum);
protected function calculateSum(string $number): int
$weight = 2;
$sum = 0;
for ($pos=strlen($number)-1; $pos>=0; $pos--) {
$tmp = $number[$pos] * $weight;
$sum += ($tmp > 9) ? (1 + ($tmp % 10)) : $tmp;
$weight = ($weight == 2) ? 1 : 2;
return $sum;
byrokrat /
checkdigit
