Modern C++ is what was in the Boost framework 15 years ago.</troll>
Joke aside, the STL grew in complexity and features to provide more compile-time constructs and to integrate more functional programming aspects.
For example: I've been told many times that in "modern C++" you don't need `new` nor `delete`.
There are smart pointers, std::array, std::optional, const-expressions, you'll find more and more "single-header" libraries (for JSON, an either monad, etc...), even modules[1].
It's like learning a new language. C++11, 14, 17 and 20 are completely different to C++03 while remaining backward compatible (a critical feature for C/C++ languages it seems).
Joke aside, the STL grew in complexity and features to provide more compile-time constructs and to integrate more functional programming aspects.
For example: I've been told many times that in "modern C++" you don't need `new` nor `delete`.
There are smart pointers, std::array, std::optional, const-expressions, you'll find more and more "single-header" libraries (for JSON, an either monad, etc...), even modules[1].
It's like learning a new language. C++11, 14, 17 and 20 are completely different to C++03 while remaining backward compatible (a critical feature for C/C++ languages it seems).
[1] - https://en.cppreference.com/w/cpp/language/modules