How did you come up with this neat solution?

The input range should be specified. Without it it's unclear what performance requirements are or what type should be used for intermediate values in C.

:D

So... considering that I have resolved the issue below, could you update the translation to include some types of test cases that were introduced with the fix? (C is something that I don't understand at all for now...)

Approved by someone

Nice job on your first kata, Alex!

both are fun and simple. the c translation has a great ability to show you some of the traps that you can encounter when learning c and even when you have experience in c.

C Translation

1. always use the spoiler flag when posting code / solutions (I have added the flag to your comment) otherwise anyone can see it
2. I suggest you make a habit of reading your error feeback very carefully:

should return "Odd" for odd positive numbers
Expected
    <string>: odd
to equal
    <string>: Odd

Recursion 🤘

uneducated?

not the same as being dumb

one of those can change

tests labeled as 'Random' are not

If we are supposed to write random_valid_key() and random_invalid_key(), then the kata description should specify that. But that doesn't make sense because we can then write trivial implementations of those functions that will make any solution pass.