7 """

  8 用一个类来实现一个节点

  9 """

 10 class Node(object):

 11     def __init__(self,data):

 12         self.data = data

 13         self.next = None

 14 class linkstack(object):

 15     def __init__(self):

 16         self.top = None

 17     def isEmpty(self):

 18         return self.top == None

 19     def clear(self):

 20         self.top = None

 21     def length(self):

 22         i = 0

 23         tempnode  =self.top

 24         while tempnode is not None:

 25             tempnode = tempnode.next

 26             i += 1

 27         return i

 28     def push(self,item):

 29         node = Node(item)

 30         node.next = self.top

 31         self.top  = node

 32     def pop(self):

 33         self.top = self.top.next

 34     def gettop(self):

 35         return self.top.data

 36     def display(self):

 37         if self.top == None:

 38             print("None")

 39         tempnode = self.top

40         while tempnode is not None:

 41             print(tempnode.data,end = " ")

 42             tempnode = tempnode.next

 43         print()

 44

 45 if __name__ == "__main__":

 46     linkstack1 = linkstack()

 47     linkstack1.push(1)

 48     linkstack1.push(2)

 49     linkstack1.push(3)

 50     linkstack1.push(4)

 51     linkstack1.push(5)

 52     linkstack1.push(6)

 53     linkstack1.display()

 54     print(linkstack1.gettop())

 55     print(linkstack1.length())

 56     linkstack1.pop()

 57     linkstack1.display()

 58     linkstack1.clear()

 59     linkstack1.display()

 60     print(linkstack1.isEmpty())