I think this code doesn't allocate enough space for the null terminator at the end of the string! As far as I can tell (from docs and quick experimentation), strlen() doesn't count the null terminator.

Using #define in modern C is not a good practice. You could use inline function, but IMHO neither was necessary in this case. Furthermore, the ? expression is totally unnecessary.

I didn't mean to start a war on characters

nope https://www.codewars.com/kumite/5dd49778ca04720028a2bcca?sel=5dd5355cd3d6c1001f71f5a9

I won https://www.codewars.com/kumite/5dd49778ca04720028a2bcca?sel=5dd498323f758800169129a8

Points for compactness!!!