GUI-based Qt applications

Returning to the Qt-based example project from Chapter 8, Example - Linux-Based Infotainment System, we can now compare its main function to the preceding command-line-only version to see what changes once we add a GUI to the project:

#include "mainwindow.h" 
#include <QApplication> 
 
int main(int argc, char *argv[]) { 
    QApplication a(argc, argv); 
    MainWindow w; 
    w.show(); 
     
    return a.exec(); 
} 

The most obvious change here is that we use QApplication instead of QCoreApplication. The other big change is that we do not use a completely custom class, but one that derives from QMainWindow:

#include <QMainWindow> 
 
#include <QAudioRecorder> 
#include <QAudioProbe> 
#include <QMediaPlayer> 
 
 
namespace Ui { 
    class MainWindow; 
} 
 
class MainWindow : public QMainWindow { 
    Q_OBJECT...