What are C macros useful for?

Question

I have written a little bit of C, and I can read it well enough to get a general idea of what it is doing, but every time I have encountered a macro it has thrown me complet

Answer 1

It's good for inlining code and avoiding function call overhead. As well as using it if you want to change the behaviour later without editing lots of places. It's not useful for complex things, but for simple lines of code that you want to inline, it's not bad.