要在属于同一种类的对象之间共享数据值，可以使用static。

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namespace demo3{     class point  //定义点    {        public int x;        public int y;    }    class line    {        static public point origin = new point();        public point ending = new point();    }        class Program    {        static void Main(string[] args)        {            line lin1 = new line();            line lin2 = new line();                        line.origin.x = 1;            line.origin.y = 5;            lin1.ending.x = 6;            lin1.ending.y = 7;            lin2.ending.x = 8;            lin2.ending.y = 9;            Console.WriteLine("1开始点 {0}{1}",line.origin.x,line.origin.y);            Console.WriteLine("1结束点  {0} {1}",lin1.ending.x,lin1.ending.y);            Console.WriteLine("2开始点 {0}{1}", line.origin.x, line.origin.y);            Console.WriteLine("2结束点  {0} {1}", lin2.ending.x, lin2.ending.y);            line.origin.x = 999;            line.origin.y = 888;            Console.WriteLine("1开始点 {0}{1}", line.origin.x, line.origin.y);            Console.WriteLine("1结束点  {0} {1}", lin1.ending.x, lin1.ending.y);            Console.WriteLine("2开始点 {0}{1}", line.origin.x, line.origin.y);            Console.WriteLine("2结束点  {0} {1}", lin2.ending.x, lin2.ending.y);            Console.ReadKey();        }    }}