Well if you want to be pedantic, C++ is actually twenty eight years old (1983), but as the language evolved a lot, modern C++ is probably less than ten years old. It depends on what you can a language and what you call a dialect.

C is indeed almost forty years old.

I've only recently found out that by "Modern C++" most people mean the way to write C++ as exposed by Alexandrescu's book on Generic Programming - is that what you mean too?