I am compiling 4 different programs, each using a lot of the same core functions and files. One of the programs requires access to a large third party library, the others do not.

I have created an "options" structure suitable for all 4 programs. The way the options structure is filled out however can differ depending on the program which is to be used. Most of it is trivial stuff... "do I write to stdout?",...

It's a bit more complicated than an array is a pointer... The explanation can be found here more eloquently than I can retype it:

http://www.lysator.liu .se/c/c-faq/c-2.html