How to set new Color every time draw() loop is executed?

[Krish]

Sorry to say but i didn't get your idea about "const QColor &color parameter". I mean how can i change their colors to distinguish them on the plot? I am using the color parameter to set curve' s color as

curve[i]->setPen(QPen(color));

curve[i]->setPen(QPen(color));

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Am calling the draw function from main file i.e. curves.cpp!!

Thanks again.