C++/CX
C++/CX (C++ component extensions) is a language projection for Microsoft's Windows Runtime platform. It takes the form of a language extension for C++ compilers, and it enables C++ programmers to write programs that call Windows Runtime (WinRT) APIs. C++/CX is superseded by the C++/WinRT language projection, which is not an extension to the C++ language; rather, it's an entirely standard modern ISO C++17 header-file-based library.
The language extensions borrow syntax from C++/CLI but target the Windows Runtime Universal Windows Platform native code instead of the Common Language Runtime and managed code. It brings a set of syntax and library abstractions that project COM's WRL subset-based WinRT programming model in a way that is intuitive to C++/CLI managed extensions' coders.
It is possible to call the Windows Runtime from native ISO C++ via the lower level Windows Runtime C++ Template Library (WRL). However, WRL is also superseded by C++/WinRT.