How do you create a GUI with C++?

Answer 1

Use Qt5

Answer 2

For Cross-Plattform: Qt
For Windows only: MFC(WinAPI)

Qt is a easy-to-learn framework, not only for GUIs, just like .NET or Java.

Windows has a great WinAPI, which lets you do cool things. The learn curve is smaller then qt's one, but it's powerful on Windows.
MFC (Microsoft Foundation Class) is a abstraction of WinAPI, especially made for GUIs.

Answer 3

Thanks