This depends a lot on what manpage you're looking at. When I learned C more than 20 years ago, I found libc manpages a pretty good way to learn. For many func

This depends a lot on what manpage you're looking at. When I learned C more than 20 years ago, I found libc manpages a pretty good way to learn. For many functions in section 3, you can read the manpage and make an intelligent guess on how it's implemented, and write your own implementation. I did this as an exercise back in the day.