What is a “private header” in C?

Question

I\'ve been learning C recently, and in one of my textbooks I found a reference to a file with the \".r\" extension. Now, as you can imagine, googling \"r\"

Answer 1

C compilers don't attach any particular meaning to file extensions, so the use of the .r extension is just the author's way of indicating something by convention. Not being familiar with the book, I don't know what that might be, but rest assured that the compiler isn't attaching any particular meaning to the file name.