Also try fprintf(stderr, "%u\n", input_value); to see your output after the tests and not to mix with them.

Sometimes it's in the same line with testing framework messages, so I recommend \n in the beginning too.

printf("%u\n", input_value); should work fine.

ocassionally it skips over some data or do not print at all

It prints everything, but it is not guaranteed that the log will appear exactly before the corresponding test. In that case try submitting again.

nope, not in any way

OK!

No problem for mislabelling! Unfortunately I don't have time to look at others' code. Maybe you could print the input to see with which zipcode you fail. Good luck!

It is a question, not an issue.
To see input in tests, print input.

You should return a block of allocated memory.