do these program in C++ or C orrr?
It's a subset of C++. Obviously, there is no keyboard, screen, or file storage in a standard Arduino, so that part of the C/C++ library is not supported. (As far as I know the STL containers are not supported either.) I assume you've found the [u]Arduino Language Referece[/u], and [u]Here[/u] is the full AVR library reference.
And, I haven't seen anyone using object oriented programming. One reason might be the limited RAM. (The program code lives in Flash, but objects are created in RAM.)