The most simple answer to this question is that you should never have used that term. It is a term that should not exist. It has no meaning. Every program is either C, or C++.
And that was quiet true until the appearance of C++x0, C++11 (or the modern C++ 11/14/17 in general).
C++98 and 03 aren't even remotely C with Classes either. Whoever taught you this doesn't know shit and you can forget them. This was never correct.
