<QWidget> #include <QPushButton> #include <QLabel> #include <QHBoxLayout> #include <QVBoxLayout> #include <QGridLayout> #include <QLineEdit> #include <QTextEdit> class MyWidget : public QWidget { Q_OBJECT public: MyWidget(QWidget *parent = 0); private: QPushButton *quit; QLabel *label1; QLabel *label2; QLineEdit *lineEdit1; QLineEdit *lineEdit2; QTextEdit *textEdit; private slots: void quitClicked(); //slot to quit the application when button is clicked. This is a private slot. It can only be accessed by other functions in this class. If you want it to be accessed by other classes, make it a public slot. See below. signals: //signals are emitted when something happens, like a button being clicked, or some data is ready, etc.. Signals are connected to slots. When the signal is emitted, the connected slots are executed. Signals and slots must have the same parameters (if any). Signals do not have return values, and they are private by default (but you can make them public). void mySignal(); //this signal does not have any parameters and does not do anything yet. We will connect this signal to quitClicked() slot so that when mySignal() is emitted, it will execute quitClicked(). Note that we don't need to declare mySignal() as a slot because it doesn't do anything yet - all we want to do is connect it to quitClicked(). We could also connect mySignal() to any other slot we want - as long as they have the same parameters (none in this case). public slots: //public slots can be accessed from other classes. They are like normal functions but they can also be connected to signals and will be executed when the signal is emitted. They can also be accessed directly like normal functions (by calling myWidget->myPublicSlot() for example). Public slots are declared with the "public slots:" keyword instead of "private slots:" which means they can be accessed from outside the class. void myPublicSlot(); //this public slot does not have any parameters and does not do anything yet. We could connect this slot to any signal we want - as long as they have the same parameters (none in this case). Note that we don't need to declare myPublicSlot() as a signal because it doesn't do anything yet - all we want to do is connect it to some signal. We could also call this function directly like a normal function (by calling myWidget->myPublicSlot() for example). };