WinRT is fundamentally COM, so using WinRT components from C is like using COM components from C. Like before, you get .idl files for all WinRT components, and also .h files produced from those .idl files. The .h files include both C++ and C declarations (wrapped in #ifdef __cplusplus as needed). You can just #include them and start hacking away.

It's not exactly neat, though, e.g. something like this C++/CX:

Windows::UI::Xaml::Controls::TextBlock^ tb = ...; tb->Text = "Foo";

which is equivalent to this vanilla C++:

Windows::UI::Xaml::Controls::ITextBlock* tb = ...; HSTRING hs; HRESULT hr = WindowsStringCreate(L"Foo", 3, &hs); // check hr for errors hr = tb->set_Text(hs); // check hr for errors tb->Release();

would be written in C as:

__x_Windows_CUI_CXaml_CControls_CITextBlock* tb = ...; HRESULT hr; HSTRING hs; hr = WindowsCreateString(L"Foo", 3, &hs); // check hr for errors hr = __x_Windows_CUI_CXaml_CControls_CITextBlock_put_Text(tb, hs); // check hr for errors IUnknown_Release(tb);

Look inside "C:\Program Files (x86)\Windows Kits\8.0\Include\winrt" in Developer Preview to see the .idl and .h files.