Qt Core is one of the modules supported by Qt. This module has loads of useful classes, such as QObject, QCoreApplication, QDebug, and so on. Almost every Qt application will require this module, hence they are linked implicitly by the Qt Framework. Every Qt class inherits from QObject, and the QObject class offers event handling support to Qt applications. QObject is the critical piece that supports the event handling mechanism; interestingly, even console-based applications can support event handling in Qt.
If you get a similar output to that shown in Figure 5.1, you are all set to get your hands dirty. Let's write our first Qt application, as shown in the following screenshot:
Figure 5.2
In the first line, we have included the QDebug header from the QtCore module. If you observe closely, the qDebug() function resembles the C++ cout ostream operator. The qDebug() function is going to be your good friend in the Qt world while you are debugging...