pset1/credit outputs the right output but fails check

Question

I'll share the printing part but not the calculation part, though happy to do that to it's just a bit lengthy.

Nonetheless marked outputs are the right/expected output when run stand-alone but fails check50. This is regardless of the input containing or not containing spaces (it's a get_long anyway)

//get checksum
total_number_sum = first_number_sum + second_number_sum;
if(total_number_sum % 10 != 0)
{
    card_type = "INVALID";
}
else if (card_number_len == 15 && card_number_digits_forward[0] == 3 && (card_number_digits_forward[1] == 4 || card_number_digits_forward[1] == 7))
{
    card_type = "AMEX";
}
else if (card_number_len == 16 && card_number_digits_forward[0] == 5 && card_number_digits_forward[0] > 0 && card_number_digits_forward[0] <= 5) 
{
    card_type = "MASTERCARD";
}
else if ((card_number_len == 13 || card_number_len == 16) && card_number_digits_forward[0] == 4)
{
    card_type = "VISA";
}
else
{
    card_type = "INVALID";
}

printf("%s\n", card_type);

Suggestions please?

Answer 1

Can't tell for sure what all the problems are because only part of the code is posted. My best guess is that there is a problem in the checksum calculations.

Along with that, there's a problem in the check for the first two digits on the mastercard numbers. It's only checking the first digit, not the second. (Probably a cut and paste error where you didn't update the index for the array.)

Without seeing the entire code, this is the best I can offer.

I will add that it's extremely unlikely that there's a problem with check50. Are you absolutely sure that you submitted the correct version of your source code? Is it possible that you're working with multiple versions of the code and submitted the wrong one? Or maybe the source code doesn't match the compiled code?

Answer 2

Found the error (albeit admittedly still not sure why they did run okay when standalone but not in check). Human logic vs code logic. Basically I initially declared

int first_number_sum , second_number_sum , total_number_sum = 0;

and assumed all three would then get to be zero. That's not the case so it throws off the checksum counts. Declaration should be

int first_number_sum = 0, second_number_sum = 0, total_number_sum = 0;