//! [0] QT -= gui //! [0] //! [1] QT += network opengl sql qt3support //! [1] //! [2] CONFIG += uic3 //! [2] //! [3] #include //! [3] //! [4] #include #include #include //! [4] //! [5] #include //! [5] //! [6] #include //! [6] //! [7] using namespace Qt; //! [7] //! [8] QLabel *label1 = new QLabel("Hello", this); QLabel *label2 = new QLabel(this, "Hello"); //! [8] //! [9] MyWidget::MyWidget(QWidget *parent, const char *name) : QWidget(parent, name) { ... } //! [9] //! [10] // DEPRECATED if (obj->inherits("QPushButton")) { QPushButton *pushButton = (QPushButton *)obj; ... } //! [10] //! [11] QPushButton *pushButton = qobject_cast(obj); if (pushButton) { ... } //! [11] //! [12] QLabel *label = new QLabel; QPointer safeLabel = label; safeLabel->setText("Hello world!"); delete label; // safeLabel is now 0, whereas label is a dangling pointer //! [12] //! [13] QT += qt3support //! [13] //! [14] DEFINES += QT3_SUPPORT //! [14] //! [15] DEFINES += QT3_SUPPORT_WARNINGS //! [15] //! [16] DEFINES += QT3_SUPPORT //! [16]