pset1 credit solution. code not working but there is no bug

Question

I wrote this code and I can "make credit". However, when I tested it with numbers, it doesn't work.

Please see my code below.

#include <cs50.h>
#include <stdio.h>
#include <math.h>

int main(void)
{
    int number = get_int("Number: ");
    int sumofln;
    int sumofeon;
    
    for (int n = 1; n < 17; n = n + 2)
    {
        int i = pow(10, n);
        int eon = number % i; //eon = every other number
        
        sumofeon = 0;
        sumofeon = sumofeon + eon; //sumofeon = sum of every other number
    }
    for (int n = 0; n < 17; n++)
    {
        int j = pow(10, n);
        int ln = number % j; //ln = left numbers
         
        sumofln = 0; //sumofln = sum of left numbers
        sumofln = sumofln + ln;
    }
    
    int total;
    total = sumofln + sumofeon;
    
    if (total % 10 == 0)
    {
        if ((number % 1000000000000000) == 4) //VISA - 16
        {
            printf("VISA\n");
        }
        else if ((number % 1000000000000000) == 5) // MASTERCARD
        {
            if ((number % 100000000000000) < 6)
            {
                printf("MASTERCAD\n");
            }
            else
            {
                printf("INVALD\n");
            }
        }
        else if (number % 1000000000000000 == 0 && number % 100000000000000 == 3) //AMEX
        {
            if (number % 10000000000000 == 4 || number % 10000000000000 == 7)
            {
                printf("AMEX\n");
            }
            else
            {
                printf("INVALID\n");
            }
        }
        else if ((number % 1000000000000000 + number % 100000000000000 + number % 10000000000000) == 0) //VISA - 13
        {
            printf("VISA\n");
        }
        else
        {
            printf("INVALID\n");
        }
    }
    else
    {
        printf("INVALID\n");
    }
}

Answer 1

One fundamental issue you'll face is that a credit card number is too long for an int; try using get_long() instead.

I would recommend starting over with your implementation of Luhn's algorithm. Something that may help: you can get the last digit of a number by using modulo 10 (% 10) and drop the last digit with integer division by 10 (/ 10).