c++小记

1、枚举类型的初始化或赋值，只能够通过气枚举成员或同一枚举类型的其他对象来进行。如：

enum Points {point2d = 2, point2w, point3d = 3, point3w};

Points pt3d = point3d;  // ok, point3d is a Points enumerator

Points pt2w = 3;          // error, pt2w initialized with int

pt2w = polygon;　　    // error, polygon is not a Points enumerator

pt2w = pt3d;              //ok, both are objects of Points enum type