Hi Guys,
i am going through the CS50 course at the moment and finished all Pset1 problems except the Credit card checker one. it does eeverything correctly except catching a credit card number that is wrong and think it’s visa instead of Invalid. Please help me with this puzzle i am in.
My code so far:
#include <stdio.h>
#include <cs50.h>
#include <math.h>
int main(void)
{
int sum = 0;
long ccNum = 0L;
while (ccNum < 1L || ccNum > 9999999999999999L)
{
ccNum = get_long("Please Input CC Number: ");
}
// Copy to be used throughout the process.
long temp = ccNum;
// Keep track of the amount and position of each digit using variable 'count'.
int count = 0;
while (temp > 0L)
{
temp = temp / 10L;
count++;
}
// Validate number of digits
if (count != 13 && count != 15 && count != 16)
{
printf("INVALID\n");
return 0;
}
// Reset value of variable 'temp' and apply calculations that will isolate the first two digits.
// Store the results in a variable 'brand'.
temp = ccNum;
while (temp > 100L)
{
temp = temp / 10L;
}
int brand = temp;
// Credit card company from ID digits and length.
if (brand > 50 && brand < 56 && count == 16)
{
printf("MASTERCARD\n") ;
}
else if ((brand == 34 || brand == 37) && (count == 15))
{
printf("AMEX\n") ;
}
else if ((brand / 10 == 4) && (count == 13 || count == 16))
{
printf("VISA\n") ;
}
else if (sum % 10 != 0)
{
printf("INVALID\n");
return 0;
}
else
{
printf("INVALID\n");
}
// Checksum.
temp = ccNum;
for (int i = 1; i <= count; i++)
{
int digit = temp % 10L;
if (i % 2 == 0)
{
digit *= 2;
if (digit > 9)
{
digit -= 9;
}
}
sum += digit;
temp /= 10L;
}
}
that was useful.