windows.ui.notifications.h vs winrt/windows.ui.notifications.h | What should i use?

Question

I have a short question about Windows 10 development with cpp:

When should i use <windows.ui.notifications.h> and when <winrt/Windows.UI.Notifications.h>, and why are there two versions of this header.

I found out that windows.ui.notifications.h is in windowssdk.......\include\winrt and <winrt/Windows.UI.Notifications.h> is in windowssdk....\include\cppwinrt.
And windows.ui.notifications.h contains also namespaces like ABI::Windows::Data::Xml::Dom; whereas <winrt/Windows.UI.Notifications.h> does not contains these namespaces but the winrt namespace. So what should i use for what??? why are there the same headers but with such differences?
-- but i thought that for example, Windows::Data::Xml::Dom should be in Windows.Data.Xml.Dom.h and not accessible via the notifications header.

Can someone please help?

Answer 1

Hello, Welcome to Micorosoft Q&A,

windows.ui.notifications.h vs winrt/windows.ui.notifications.h | What should i use?

It is based on which namespace is selected for your uwp language. If you was using C++CX, please include windows.ui.notifications.h, And if you are using C++WinRT, please include winrt/windows.ui.notifications.h. Or it will throw head file not found exception.

And windows.ui.notifications.h contains also namespaces like ABI::Windows::Data::Xml::Dom;

A Windows Runtime class (runtime class) is really an abstraction. This abstraction defines a binary interface (the Application Binary Interface, or ABI) that allows various programming languages to interact with an object. Regardless of programming language, client code interaction with a Windows Runtime object happens at the lowest level, with client language constructs translated into calls into the object's ABI.

For more please refer this document.

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