Tangent: Looking at those code samples, I wonder whether coming up with the shortest possible, most cryptic variable names is somewhat of a sport amongst C developers. Are you guys still coding in Notepad and need to conserve keystrokes, or where does that reluctance to use proper names come from?
Just inertia from the times where teletypes were a thing. As in, a mechanical printer that served as your console. When you have that as your interface you want to keep things terse. Even after that you had compilers with limits like 6 character names for a symbol. Those constraints went away, but names made to be comfortable for the users of teletypes and ancient compilers stuck around, and people made more of them…
No. I like these names as it's just easier to read. fp or fd is short and to the point, and "filePointer" or variants thereof add noting except more characters to read, more "wall of text"-y code that's harder to scan, etc.
And I don't really want to have a discussion about it as such; whatever your preference is that fine. I'll be happy to adjust to whatever works well within a team. But I wish people would stop spreading nonsense like this to invalidate other people's preferences.