global variables instead of pointers and data structures

While I was writing the program I noticed that I had a distinct issue: I couldn't figure out how to use one function which calls different variables for help without either passing many values through multiple functions each defined with many, many parameters or setting up a bunch of global variables. For my skill level, even though I knew it's considered bad practice, it seemed like the path of least resistance to use globals. Anyway, I think, after doing some research and chatting with Harry, that pointers are a concept I haven't learned yet that might solve my problems.

The issue does not name files, tests, or an entry point. First clarify which globals and functions are in scope and whether the goal is pointers, data structures, or both; done would require an agreed design and verified program behavior.

Written by the indexing model from the issue text.