C#类型转换

§LinemyLine = (Line)myObject;

§‘as’操作符-Line myLine = myObjectasLine; - 

    §如果失败，没有异常，但对象为null !

§‘is’操作符–if  (myObj is Line) …

§typeof操作符 – if typeof (obj1) == typeof(obj2)…

§GetType - If obj1.GetType()  == obj2.GetType() …