Headers include in multiple C files

Question

I have two files foo.c and bar.c that I compile separately with gcc -c and then link. Both files need the stdio.h and stdlib.h headers.

Do I have to in

Answer 1

You will have to include the header in any file which is compiled by itself even if you will be linking it later.
There is already an #ifdef in the header so that it will only be actually used once.