I last used C professionally around 1997 IIRC. I've used a lot of C++ since then. Now, I find I need to use some C again.
One thing I'm sure of is that I can't just drop the obvious C++ features (e.g. classes) and expect everything to work. There are various less obvious syntax changes. I just don't remember what they are.
Is there a good reference for making that transition again, but returning to C? If it explains the changes in C99 (and later?) that's even better.