I downvoted just because I thought it wasn't great advice. It makes the code incompatible with C++ compilers, and being able to compile C with C++ compiler is often useful.
Also... it felt kind of... unnecessary? to tell someone who is making a compiler how to write basic code in the language they're writing a compiler for. It almost felt like telling an overweight medical student/doctor that he should avoid eating fatty foods.
Not sure why I was down-voted, I think that is ... not nice. :(