plot.cpp

#include <QtGui>

#include <qwt_plot.h>
#include <qwt_plot_curve.h>

int main (int argc, char** argv)
{
    QApplication app( argc, argv );

        QwtPlot plot;
        QwtPlotCurve curve;

        curve.setSamples( QVector<QPointF>
                { QPointF(1, 1), QPointF(2, 3), QPointF(3, 2), QPointF(4, -1) } );
        curve.attach( &plot );
        plot.show();
        qDebug() << plot.axisInterval( QwtPlot::xBottom );

    return app.exec();
}