The QFile class provides an interface for reading from and writing to files.| doc.qt.io
The QEvent class is the base class of all event classes. Event objects contain event parameters.| doc.qt.io
The QUrl class provides a convenient interface for working with URLs.| doc.qt.io
The QApplication class manages the GUI application's control flow and main settings.| doc.qt.io
The QCoreApplication class provides an event loop for Qt applications without UI.| doc.qt.io