python实现一个简易版学生成绩管理系统
300来行代码
使用链表来实现
class Node(object):
def __init__(self, data, pointer):
self.data = data
self.next = pointer
# 创建单链表
class SingleLinkedList(object):
def __init__(self):
self.head = Node(None, None)
self.point = self.head
def append(self, data):
# 末尾追加节点
new_node = Node(data, None)
self.point.next = new_node
self.point = new_node
def insert(self, data, find):
# 插入数据(前向插入数据)
if not self.head.next:
print('链表为空')
return None
new_node = Node(data, None)
self.point = self.head
while self.point.next.data != find:
self.point = self.point.next
if self.point.next is None:
print('没有找到该元素')
return None
new_node.next = self.point.next
self.point.next = new_node
def delete(self, find):
# 删除节点
# 空链表
if not self.head.next:
print('链表为空')
return None
self.point = self.head
while self.point.next.data != find:
self.point = self.point.next
pointer = self.point.next
self.point.next = self.point.next.next
del pointer
def insert_after_head(self, data):
node = Node(data, None)
# bug 产生没写 if 返回
if not self.head.next:
self.head.next = node
return None
node.next = self.head.next
self.head.next = node
def reverse(self):
local_list = SingleLinkedList()
self.point = self.head
count = 0
while self.point.next:
count += 1
self.point = self.point.next
data = self.point.data
local_list.insert_after_head(data)
return local_list
def get_size(self):
count = 0
self.point = self.head
while self.point.next:
self.point = self.point.next
count += 1
return count
def delete_by_tail(self, num):
size = self.get_size()
assert (num <= size)
assert (num > 0)
pos = size - num
count = 0
self.point = self.head
while count < size:
count += 1
self.point = self.point.next
if count == pos:
pointer = self.point.next
self.point.next = self.point.next.next
del pointer
# 求中间节点 只允许遍历一次
def quick_middle(self):
slow_point = self.head
fast_point = self.head
while fast_point.next.next:
slow_point = slow_point.next
fast_point = fast_point.next.next
if not fast_point.next:
break
if fast_point.next:
slow_point = slow_point.next
return slow_point.data
def check_circle(self):
pass
def sort(self):
# get_size()改变了 self.point 的指向
length = self.get_size()
i, j = 0, 0
flag = 1
while i < length:
self.point = self.head.next
while j < length - i - 1:
if self.point.data > self.point.next.data:
temp = self.point.data
self.point.data = self.point.next.data
self.point.next.data = temp
self.point = self.point.next
j += 1
flag = 0
if flag:
break
i += 1
j = 0
def print(self):
# 打印结点
self.point = self.head
while self.point.next:
self.point = self.point.next
print('{} ->'.format(self.point.data), end=' ')
print('')
class StudentControlSystem(SingleLinkedList):
# 打印菜单
def print_menu(self):
print('*' * 30)
print('-' * 13 + '菜单' + '-' * 13)
print('1.增加学生信息')
print('2.删除学生信息')
print('3.修改学生信息')
print('4.查找学生信息')
print('5.显示所有信息')
print('6.排序')
print('0.退出程序')
print('*' * 30)
# 用户输入
def user_input(self, item):
try:
item = int(item)
except:
pass
# 增加信息
if item == 1:
self.add_info()
# 删除信息
elif item == 2:
find = input('请输入删除的学号：')
self.del_info(find=find)
# 修改信息
elif item == 3:
self.modify_info()
# 查找信息
elif item == 4:
self.search_info()
# 显示信息
elif item == 5:
self.display_info()
# 信息排序
elif item == 6:
self.rank_info()
# 退出程序 保存数据
elif item == 0:
with open('database.txt', 'w') as f:
self.point = self.head
while self.point.next:
self.point = self.point.next
f.writelines('{}\n'.format(self.point.data))
exit()
else:
print('请输入正确的数字')
# id 保证互异性
def unique_id(self, std_id):
self.point = self.head
while self.point.next:
self.point = self.point.next
if self.point.data['id'] == std_id:
return False
return True
# 增加信息
def add_info(self):
# id 不能重复
# 成绩不能超出范围
name = input('姓名：')
std_id = input('学生id：')
while not self.unique_id(std_id=std_id):
print('id重复')
std_id = input('学生id：')
grade = input('学生成绩：')
if eval(grade) < 0 or eval(grade) > 100:
print('超出范围')
grade = input('学生成绩：')
print(name, std_id, grade)
print('请确认无误后保存')
choice = input('y/n')
items = ['y', 'yes', 'Y', 'Yes']
if choice in items:
print(choice)
data = {'id': std_id, 'name': name, 'grade': grade}
self.append(data)
# 删除信息
def del_info(self, find):
print('请确认无误后保存')
choice = input('y/n')
items = ['y', 'yes', 'Y', 'Yes']
if choice in items:
if not self.head.next:
print('链表为空')
return None
self.point = self.head
while self.point.next.data['id'] != find:
self.point = self.point.next
pointer = self.point.next
self.point.next = self.point.next.next
del pointer
# 序列逆序
def reverse(self):
local_list = StudentControlSystem()
self.point = self.head
count = 0
while self.point.next:
count += 1
self.point = self.point.next
data = self.point.data
local_list.insert_after_head(data)
return local_list
# 序列排序
def sort(self, item):
length = self.get_size()
i, j = 0, 0
flag = 1
while i < length:
self.point = self.head.next
while j < length - i - 1:
if int(self.point.data[item]) > int(self.point.next.data[item]):
# self.point.data, self.point.next.data =
# self.point.next.data, self.point.data
temp = self.point.data
self.point.data = self.point.next.data
self.point.next.data = temp
self.point = self.point.next
j += 1
flag = 0
if flag:
break
i += 1
j = 0
# 修改信息
def modify_info(self):
find = input('输入需要修改的学生的id：')
if not self.head.next:
print('链表为空')
return None
self.point = self.head
while str(self.point.next.data['id']) != find:
self.point = self.point.next
if self.point.next is None:
print('没有找到该元素')
return None
name = input('姓名：')
grade = input('学生成绩：')
self.point.next.data['name'] = name
self.point.next.data['grade'] = grade
# 搜索信息
def search_info(self):
find = input('输入需要查找的学生的id：')
if not self.head.next:
print('链表为空')
return None
self.point = self.head
while str(self.point.next.data['id']) != find:
self.point = self.point.next
if self.point.next is None:
print('没有找到该元素')
return None
data = self.point.next.data
print('ID 姓名 成绩')
print('{} {} {}'.format(data['id'], data['name'], data['grade']))
# 信息排序
def rank_info(self):
choice = input('1.成绩排序 2.学号排序：')
order = input('1.升序 2.降序：')
if choice == '1':
item = 'grade'
elif choice == '2':
item = 'id'
else:
return None
self.sort(item=item)
if order == '2':
temp = self.reverse()
temp.display_info()
return None
self.display_info()
# 显示信息
def display_info(self):
self.point = self.head
print('ID 姓名 成绩')
while self.point.next:
self.point = self.point.next
data = self.point.data
print('{} {} {}'.format(data['id'], data['name'], data['grade']))
print('')
def main():
SCS = StudentControlSystem()
try:
with open('database.txt', 'r') as f:
for data in f.readlines():
SCS.append(eval(data))
except:
with open('database.txt', 'w') as f:
pass
while True:
SCS.print_menu()
item = input('请输入你的选择：')
SCS.user_input(item)
if __name__ == "__main__":
main()
运行后
然后就可以插入与查询啦