The document describes adding member variables and initialization code to a CLineView class. It instructs to declare integer variables x and y as public members, initialize them to 0 in the constructor, and update x and y to the mouse click coordinates on a left button down message to draw a line from the initial point to the clicked point.

1. Line

5. Add the folowing member variables:
………………
DECLARE_MESSAGE_MAP()
public:
int x;
int y;
};
Var name Var type Class Access type
x int CLineView public
y int CLineView public

6. • Initialize the var in the constructor of the
CLineView class:
CLineView::CLineView() noexcept
{
// TODO: add construction code here
x = 0;
y = 0;
}

10. void CLineView::OnLButtonDown(UINT nFlags,
CPoint point)
{
// TODO: Add your message handler code here
//and/or call default
CClientDC dc(this);
dc.MoveTo(x, y);
dc.LineTo(point.x, point.y);
x = point.x;
y = point.y;
CView::OnLButtonDown(nFlags, point);
}