IMO, the classic C++ book/author is still the best: Effective C++. Don't forget about the sequels, including the mostly overlooked Effective STL (which I happen to like better than the first two books). And to address the modern part of this question, I'll add that Scott Meyers has written Effective Modern C++ as well, but I'd read that last after getting the hang of C++03. No matter what people say, I tend to believ…
As someone who programmed in "classic C++" for decades, I feel like modern C++ is pretty different, and that it's not just syntactic sugar to make some ugly things easier. The biggest example is that my natural inclination to use raw pointers everywhere and manage all memory myself, while idiomatic modern C++ is full of unique_ptrs and shared_ptrs everywhere, and raw pointers seem to be regarded as a code smell. Conv…
They are not free and prevent certain kinds of optimization as well as allow accidentally sharing state.