我正在尝试使用 Luhn 的算法来检查有效的信用卡，但我无法将数字相加

Question

我试图用 Luhn 算法用这个信用卡号得到总和：4003600000000014

我得到这个输出： 单数求和：4195600 乘数：0

我正在尝试获得 13 和 7...

感谢一些帮助！

#include <stdio.h>

int main(void)
{
    do
    {
        long card_number = get_long("Write your card's number:");
    } while (card_number < 0);

    // Sum of numbers that wont be multiplied by two
    int non_mult_numbers = card_number;
    while (non_mult_numbers > 0)
    {
        int last_digit = non_mult_numbers % 10;
        int sum_non_mult_numbers = sum_non_mult_numbers + last_digit;
        non_mult_numbers = non_mult_numbers / 100;
    }
    printf("Sum single numbers: %i\n", sum_non_mult_numbers);

    // Sum of numbers that will be multiplied by two and their digits added
    int mult_numbers = card_number;
    mult_numbers = mult_numbers / 10;
    while (mult_numbers > 0)
    {
        last_digit = mult_numbers % 10;
        int digit_times_two = last_digit * 2;
        int add_digits = add_digits + digit_times_two % 10 + digit_times_two / 10;
        mult_numbers = mult_numbers / 100;
    }
    printf("Multiplied numbers: %i\n", add_digits);
}

Answer 1

虽然您的代码无法编译，但我假设您的几个变量的作用域/生命周期有误。

检查 add_digits、sum_non_mult_numbers、card_number。

关注 {} 为内部定义的变量标记范围边界这一事实。