Luhn.php
1.21 KB
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<?php
namespace Faker\Calculator;
/**
* Utility class for generating Luhn checksum and validating a number
*
* Luhn algorithm is used to validate credit card numbers, IMEI numbers, and
* National Provider Identifier numbers.
*
* @see http://en.wikipedia.org/wiki/Luhn_algorithm
*/
class Luhn
{
/**
* @return int
*/
private static function checksum($number)
{
$number = (string) $number;
$length = strlen($number);
$sum = 0;
for ($i = $length - 1; $i >= 0; $i -= 2) {
$sum += $number{$i};
}
for ($i = $length - 2; $i >= 0; $i -= 2) {
$sum += array_sum(str_split($number{$i} * 2));
}
return $sum % 10;
}
/**
* @return string
*/
public static function computeCheckDigit($partialNumber)
{
$checkDigit = self::checksum($partialNumber . '0');
if ($checkDigit === 0) {
return 0;
}
return (string) (10 - $checkDigit);
}
/**
* Checks whether a number (partial number + check digit) is Luhn compliant
*
* @return boolean
*/
public static function isValid($number)
{
return self::checksum($number) === 0;
}
}