我是python新手，一直在尝试学习简单的数据结构。我已经能够为一个链表拼凑出一些函数，并且我的delete函数遇到了问题。下面列出了有问题的函数和测试用例：类节点：definit（self，initial_data）：self。数据=初始数据自身。下一个=无
def get_data(self):
return self.data
def get_next(self):
return self.next
def set_data(self, new_data):
self.data = new_data
def set_next(self, new_next):
self.next = new_next
类LinkedList:def init（self）：self。头=无
def __str__(self):
output_string = ''
current = self.head
while current is not None:
output_string += str(current.get_data())
next_node = current.get_next()
#gives the pointer to the next node i.e. the next node is that which is next to the current
if next_node is not None:
output_string += "->"
current = next_node
return output_string
#does not need to be changed for ordered linked list
def is_empty(self):
if self.head is None:
return True
else:
return False
def insert(self, data):
current = self.head
previous = None
stop = False
while current != None and not stop:
if current.get_data() > data:
stop = True
else:
previous = current
current = current.get_next()
temp = Node(data)
if previous == None:
temp.set_next(self.head)
self.head = temp
else:
temp.set_next(current)
previous.set_next(temp)
#does not need to be changed for ordered linked list
def size(self):
current = self.head
count = 0
while current != None:
count += 1
current = current.get_next()
return count
def search(self, item):
current = self.head
found = False
stop = False
while current is not None and not found and not stop:
if current.get_data() == item:
found = True
else:
current = current.get_next()
return found
def delete(self, item):
current = self.head
previous = None
found = False
while not found:
if current.get_data() == item:
found = True
else:
previous = current
current = current.get_next()
if previous is None:
self.head = current.get_next()
else:
previous.set_next(current.get_next())
def test_nonexistent():
my_list = LinkedList()
my_list.insert(31)
my_list.insert(77)
my_list.insert(17)
my_list.insert(93)
my_list.insert(26)
my_list.insert(54)
assert my_list.size() == 6
my_list.delete(77)
my_list.delete(1)
assert my_list.size() == 5
我收到了错误信息
"属性错误：'NoneType'对象没有属性'get_data'和删除函数"
我认为delete函数有点问题，因为它不能处理列表中没有的值，但是我现在很困惑如何让它工作。感谢您的帮助！
您正在使用无来指示列表中没有其他节点，即您在最后，但是在搜索列表时您从来没有测试过，所以当您到达最后时，您尝试调用N<-_data代码。解决办法：不要那样做。
返工循环的一个好方法可能是将while循环更改为testcurrent，并在找到项目时使用break退出循环。
while current is not None:
if current.get_data() == item:
break
else:
previous = current
current = current.get_next()
您需要重做一些后面的逻辑来解释这一点。您不需要单独的找到标志；您可以简单地检查当前。如果是无，则到达列表末尾时没有找到要查找的项。否则，你找到了它，而当前就是它。
这有点难理解，因为您还没有发布实际的LinkedList，但我假设您正在调用current。get_next（）次数太多，可能会到达列表的末尾。也许像这样的东西对你有魔力（更新）：
def delete(self, item):
current = self.head # we don't need the previous variable
previous = None
found = False
while current is not None and not found:
if current.get_data() == item:
found = True
else:
previous = current
current = current.get_next()
# at this point we should have either reached to end of the list
# and current is None
# or we have found the node we were looking for
if found and previous is not None:
# delete it
previous.set_next(current.get_next())
elif found and previous is None:
# removing head element
self.head = None
else:
# nothing found
print("Do whatever you want here")
