plotting just points and without any lines between them

[Alex22]

Hi,
(I have asked my question here and sorry for bad position selecting for asking. I think here is suitable for my basic question).

I have two questions. 1- when plotting like below example, points be connected together by lines. I need the points be plotted and there be no line. 2- my data is too huge and i want to use float instead of double but setSamples function gives two "QVector< double > &" . is it possible to use QVector< float > & ???
for example:

QVector<double> v(10);
        QwtPlot p;
        QwtPlotCurve c;
 
        v<<0<<1<<2<<3<<4<<5<<6<<7<<8<<9;//1-is it possible only this points be showed without any line between them?
 
        c.setSamples(v, v);//2-how could i use Qvector<float> instead of Qvector<double>?
        c.attach(&p);
 
        p.show();

QVector<double> v(10);
        QwtPlot p;
        QwtPlotCurve c;
     
        v<<0<<1<<2<<3<<4<<5<<6<<7<<8<<9;//1-is it possible only this points be showed without any line between them?
     
        c.setSamples(v, v);//2-how could i use Qvector<float> instead of Qvector<double>?
        c.attach(&p);
     
        p.show();

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thanks for any help