how to create functions that use var.func()

So this is a pretty newbie question and im pretty sure it has something to do with classes. I am looking for a way to create functions with the variable being set before the function

examples of these are: string.length(); string.indexOf(); lcd.print();

i tried reading a book on basics of functions and classes however i found it completly useless and glossed over classes.

Can you tell me your experience on C/C++ and/or any other languages that you fell comfortable with?

This one seemed pretty good to me:

The search terms that you're looking for are class (see above) and struct.

Structs come from the C language, classes are the C++ successors of structs. C++ supports both and you will find a lot of structs in Arduino related code.