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c++qtqlist

how to change the value of a color in a qlist

I had an object of a Circle, it contains the properties to draw it like width, coor xy, color. I had a qlist of this circles(objects) but when i try to change the color i get an error.

class Circle {
 int x;
 int y;
 int width;
 QColor color
}

QList <Circle> circles;

I add some circles to the list here is the problem

circles.at(3).color = Qt::yellow;

passing ‘const QColor’ as ‘this’ argument of ‘QColor& QColor::operator=(Qt::GlobalColor)’ discards qualifiers [-fpermissive]

Solution

  • The at() function of a QList returns a const reference: const T & QList::at(int i) const, so you can not modify it. Use operator[] instead: circles[3].color = Qt::yellow

    Also note that right now all members of your class are private (by default), so you will not be able to set color anyway.