This is an example of a module.

string-stuff.h: one-line declarations for several string functions
string-stuff.c: the actual function bodies for those functions
main.c:         code that uses the string functions


Compile it like this:

    c99 -Wall main.c string-stuff.c

or like this:

    c99 -Wall -c main.c
    c99 -Wall -c string-stuff.c
    c99 main.o string-stuff.o

or like this:

    make