书上练习题:说是下面这段代码可以编译,就是不能像预期一样工作,让找出问题所在
书上练习题:说是下面这段代码可以编译,就是不能像预期一样工作,让找出问题所在:

namespace BuildingLibrary

{

    class PropertyLine

    {

        bool SharesEndpointWith(PropertyLine other)

        {

            XYZ startPoint = other.GetEndPoint(0);

            XYZ endPoint = other.GetEndPoint(1);



            return startPoint.ArePointsCoincident(m_startPoint) || 

                   endPoint.ArePointsCoincident(m_endPoint);

        }



        XYZ GetEndPoint(int index)

        {

            return (index == 0 ? m_startPoint : m_endPoint);

        }



        private XYZ m_startPoint;

        private XYZ m_endPoint;

    }



    class XYZ

    {

        public bool ArePointsCoincident(XYZ otherXYZ)

        {

            return (X == otherXYZ.X && Y == otherXYZ.Y && Z == otherXYZ.Z);

        }



        public double X

        {

            get { return m_X; }

        }



        public double Y

        {

            get { return m_Y; }

        }



        public double Z

        {

            get { return m_Z; }

        }



        private double m_X, m_Y, m_Z;

    }

}

看了半天没看出来,大家伙帮忙看看,不知道是哪儿有问题呀
------解决方案--------------------
 public bool ArePointsCoincident(XYZ otherXYZ)
        {
            return (X == otherXYZ.X && Y == otherXYZ.Y && Z == otherXYZ.Z);
        }
 
        public double X
        {
            get&n