std::reverse on MFC CArray

Question

I have an array of points like this:

CArray<CPoint,CPoint> points;

And I need to reverse the order of the points. I've tried this method:

std::reverse( &points[0], &points[0] + points.GetSize() );

And it works. Then I've tried this other method:

std::reverse( &points[0], &points[points.GetUpperBound()] );

But it doesn't work: the last item is not ordered correctly. Why?

Answer 1

That is because STL algorithms take ranges in the form [b, e) (that is, e exclusive), whereas the function you used returns the position of the last actual last element.

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It should be further noted that your second form is even more problematic in the case where the array is empty. The function, according to the documentation, returns -1 in this case. BOOM!