Learning C++ on KDE Neon
A good resource for learning C++ is the Learn CPP website. It is aimed at Linux users as well as others and has 18 chapters with almost 200 tutorials on C++ concepts.
There are also open source textbooks available which can be found at sites such as;
The links given should arrive on the C++ search results.
There are also a number of IDE's that can be used to write C++ code on KDE neon.