#define RUNTIME_CLASS(class_name)\
#if class_name!=NULL \
((CRuntimeClass*)(&class_name::class##class_name))\
#else \
class_name=NULL;\
#endif


总体思路就是
如果class_name参数不要等于0 就执行((CRuntimeClass*)(&class_name::class##class_name))
如歌class_name等于0 就执行class_name=NULL


急用