What is QTextStream and how can you reuse it?

 The QTextStream class provides a convenient interface for reading and writing text. So far we have used QTextStreams to move data to or from a text file, to standard out (the screen), from standard in (the keyboard) and to a QString.

What is the purpose of the QT variable in the qmake project file? What are possible values?

  It specifies which Qt modules will be enabled for this project. Possible values are gui, xml, sql, and net. core is enabled by default.

Why should you use QTextStream instead of iostream in your programs?

 <QTextStream> works with Unicode QStrings and other Qt types. iostream does not work with any Qt types.