class A:

     def __init__(self,name='Andy'):

         self._name = name 

 class B:

     def __init__(self,name = 'Jack',age=19):

         self.__name = name  # 私有属性(变量)，只有类对象自己能访问，子类也不能访问

         self._age = age     # 保护变量，类，及子类对象可以访问

 class C(B):

     def h(self):

         print('hello')

 a = A()

 b = B()

 c = C()

 print(a._name)  # 输出Adny

 print(b._B__name)   # 私有属性在类外的访问方式：对象._类__属性名

 print(c._age)   # 输出19

 print(c._C__name)   # AttributeError: 'C' object has no attribute '_C__name'子类不能访问