c++ - //! [0] in Qt source code -

what meaning of //! [n] (n = 0, 1, 2 ...) markup in c++/qml sources in qt sample projects?

for example:

//! [0] glwidget::glwidget(helper *helper, qwidget *parent)     : qglwidget(qglformat(qgl::samplebuffers), parent), helper(helper) {     elapsed = 0;     setfixedsize(840, 400);     setautofillbackground(false); } //! [0]  //! [1] void glwidget::animate() {     elapsed = (elapsed + qobject_cast<qtimer*>(sender())->interval()) % 1000;     repaint(); } //! [1]  //! [2] void glwidget::paintevent(qpaintevent *event) {     qpainter painter;     painter.begin(this);     painter.setrenderhint(qpainter::antialiasing);     helper->paint(&painter, event, elapsed);     painter.end(); } //! [2] 

despite common misconception, qdoc syntax, not doxygen. comment documentation purposes in qt project mark example snippets rendered so. not documented well, here can find corresponding code implements feature.

as end user of qt, not need deal unless start contributing qt project or trying reuse qdoc own project, admittedly odd @ point.