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<?php
declare(strict_types = 1);
namespace byrokrat\banking\Validator;
use byrokrat\banking\Exception\LogicException;
/**
* Modulo11 calculator
*/
class Modulo11
{
* Map modulo 11 remainder to check digit map
private const REMAINDER_TO_CHECK_DIGIT_MAP = [
0 => '0',
1 => '1',
2 => '2',
3 => '3',
4 => '4',
5 => '5',
6 => '6',
7 => '7',
8 => '8',
9 => '9',
10 => 'X',
11 => '0',
];
* Calculate the modulo 11 check digit for number
*
* @throws LogicException If $number is not numerical
public static function calculateCheckDigit(string $number): string
if (!ctype_digit($number)) {
throw new LogicException(
"Number can only contain numerical characters, found '$number'"
);
}
$sum = 0;
foreach (array_reverse(str_split($number)) as $pos => $digit) {
$sum += $digit * self::getWeight($pos, 2);
// Calculate check digit from remainder
return self::REMAINDER_TO_CHECK_DIGIT_MAP[11 - $sum % 11];
* Calculate weight based on position in number
* @param int $pos Position in number (starts from 0)
* @param int $start Start value for weight calculation (value of position 0)
protected static function getWeight(int $pos, int $start = 1): int
$pos += $start;
while ($pos > 10) {
$pos -= 10;
return $pos;
byrokrat /
banking
