[gvajravelu]

The book structure depends on your goals for the reader.

Books that are for teaching a skill to a beginner generally follow a project based approach. You start with a basic concept and have the reader build a project. Then you go on to a more advanced topic and have the reader build a more advanced project. It would be great if each project built upon the previous ones. I think that is one reason why Michael Hartl's Ruby on Rails Tutorial is so popular: https://www.railstutorial.org/book.

Then there are reference books. These are for experienced people to go back and relearn a concept they forgot. These books are great when organized with a clear table of contents for easily looking up topics. They don't need elaborate projects, but they do need examples to demonstrate the application of the concept. Something like the C++ reference would fall into this category: http://www.cplusplus.com/reference/clibrary/.

Hope that helps. Good luck!