c4 - C in four functions

An exercise in minimalism.

Try the following under GNU/Linux:

gcc -o c4 c4.c  (you may need the -m32 option on 64bit machines)
./c4 hello.c
./c4 -s hello.c

./c4 c4.c hello.c
./c4 c4.c c4.c hello.c

Try the following under Microsoft Windows/Visual Studio 2017 in the "x86 Native Tools Command Prompt for VS 2017" or "x64_x86 Cross Tools Command Prompt for VS 2017":

cl c4.c
c4 hello.c
c4 -s hello.c

c4 c4.c hello.c
c4 c4.c c4.c hello.c