123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051 |
- <?php
- /*
- * By adding type hints and enabling strict type checking, code can become
- * easier to read, self-documenting and reduce the number of potential bugs.
- * By default, type declarations are non-strict, which means they will attempt
- * to change the original type to match the type specified by the
- * type-declaration.
- *
- * In other words, if you pass a string to a function requiring a float,
- * it will attempt to convert the string value to a float.
- *
- * To enable strict mode, a single declare directive must be placed at the top
- * of the file.
- * This means that the strictness of typing is configured on a per-file basis.
- * This directive not only affects the type declarations of parameters, but also
- * a function's return type.
- *
- * For more info review the Concept on strict type checking in the PHP track
- * <link>.
- *
- * To disable strict typing, comment out the directive below.
- */
- declare(strict_types=1);
- function isValid(string $number): bool {
- $number = str_replace(' ', '', $number);
- if (mb_strlen($number) < 2) {
- return FALSE;
- }
- if (preg_match("/\D/", $number)) {
- return FALSE;
- }
- // At this point, we know the string only contains digits, so ASCII.
- $digits = str_split($number);
- $sum = 0;
- $len = count($digits);
- for ($i = $len - 1; $i >= 0; $i--) {
- $digit = $digits[$i];
- if (($len - $i) % 2 == 0) {
- $digit *= 2;
- if ($digit > 9) {
- $digit -= 9;
- }
- }
- $sum += $digit;
- $sum %= 10;
- }
- return ($sum % 10) === 0;
- }
|