class Node:
   def __init__(self, my_data):
      self.prev = None
      self.data = my_data
      self.next = None
class count_val:
   def __init__(self):
      self.head = None
      self.tail = None
   def add_data(self, my_data):
      new_node = Node(my_data)
      if(self.head == None):
         self.head = self.tail = new_node;
         self.head.previous = None;
         self.tail.next = None;
      else:
         self.tail.next = new_node;
         new_node.previous = self.tail;
         self.tail = new_node;
         self.tail.next = None;
   def count_node(self):
      my_counter = 0;
      curr = self.head;
      while(curr != None):
         my_counter = my_counter + 1;
         curr = curr.next;
      return my_counter;
   def print_it(self):
      curr = self.head
      if (self.head == None):
         print("该列表为空")
         return
      print("节点为 :")
      while curr != None:
         print(curr.data)
         curr = curr.next
my_instance = count_val()
print("正在向列表中添加元素")
my_instance.add_data(10)
my_instance.add_data(14)
my_instance.add_data(24)
my_instance.add_data(17)
my_instance.add_data(22)
my_instance.print_it()
print("双向链表中的节点为 : ")
print(my_instance.count_node())

正在向列表中添加元素
节点为 :
10
14
24
17
22
双向链表中的节点为 :
5