Now I'm trying example 1 of the book, which starts with #include <QApplication>. VS can't find that. Anybody know what I'm supposed to put in my "include"project settings?
Sorry, but this is one of the things that you cannot just transfer from a Qt4 book to Qt5. Modules have been introduced, so QtWidgets are not the default and your project must explicitly specify that it wants to use it. Using a Qt5 book for learning to program with Qt5 is definitely preferable.