How can I split up my monolithic programs into smaller, separate files?

Question

In all the code I see online, programs are always broken up into many smaller files. For all of my projects for school though, I\'ve gotten by by just having one gigantic C sour

Answer 1

Easy of reading is one point of breaking up files, but another is that when you build a project containing multiple files (header and source files) a good build system will only rebuild the files that have been modified thereby shortening build-times.

As for how to break up a monolithic file into multiple files, there are many ways to go. Speaking for me, I would try to group functionality, so for example all input handling is put in one source file, output in another, and functions that are used by many different function in a third source file. I would do the same with structures/constants/macros, group related structures/etc. in separate header files. I would also mark functions used only in a single source file as static, so they can't be used from other source files by mistake.