功能代码块

Posted 2020-12-26 rongge95500

二分法

想从一个按照从小到大排列的数字列表中找到指定的数字，遍历的效率太低，用二分法（算法的一种）可以极大缩小问题规模

 1 l=[1,3,5,8,12,34,45,56,67,78,89,123,234,345,456,566,789]
 2 def find(find_num,l):
 3     print(l)
 4     if len(l)==0:
 5         print(‘not find‘)
 6         return
 7     mid_index=len(l)//2
 8     if find_num>l[mid_index]:
 9         l=l[mid_index+1:]
10         find(find_num,l)
11     elif find_num<l[mid_index]:
12         l=l[:mid_index]
13         find(find_num,l)
14     else:
15         print(‘find it‘)
16 find(45,l)

View Code

购物车项目

  1 import os
  2 
  3 product_list = [[‘Iphone7‘, 5800],
  4                 [‘Coffee‘, 30],
  5                 [‘疙瘩汤‘, 10],
  6                 [‘Python Book‘, 99],
  7                 [‘Bike‘, 199],
  8                 [‘ViVo X9‘, 2499],
  9                 ]
 10 
 11 DB = r‘bc.txt‘
 12 shopping_cart = {}
 13 user_info = []
 14 
 15 while True:
 16     print(‘‘‘
 17     1: register
 18     2: login
 19     3: shopping
 20     ‘‘‘)
 21 
 22     choice = input(‘请选择>>:‘).strip()
 23     if choice == ‘1‘:
 24         print(‘register‘)
 25         while True:
 26             name = input(‘输入用户名>>:‘).strip()
 27             pwd = input(‘输入密码>>:‘).strip()
 28             conf_pwd = input(‘再次输入密码>>:‘).strip()
 29             if not pwd == conf_pwd:
 30                 print(‘密码输入错误‘)
 31                 continue
 32             print(‘注册成功‘)
 33 
 34             balance = input(‘请输入充值金额>>:‘).strip()
 35             print(‘充值成功‘)
 36             break
 37         with open(DB, ‘at‘, encoding=‘utf-8‘) as f:
 38             f.write(‘%s|%s|%s‘ % (name, pwd, balance))
 39             f.flush()
 40 
 41 
 42     elif choice == ‘2‘:
 43         print(‘login‘)
 44         count = 0
 45         tag = True
 46         if count == 3:
 47             print(‘尝试次数过多，退出。。。‘)
 48             break
 49         while tag:
 50             name = input(‘输入用户名>>:‘).strip()
 51             pwd = input(‘输入密码>>:‘).strip()
 52             with open(DB, ‘r‘, encoding=‘utf-8‘) as f:
 53                 for line in f:
 54                     # 将字符串切成列表
 55                     line = line.strip(‘
‘)
 56                     info_line = line.split(‘|‘)
 57 
 58                     # 分别取出用户名、密码、余额
 59                     db_name = info_line[0]
 60                     db_pwd = info_line[1]
 61                     db_balance = int(info_line[2])
 62 
 63                     if name == db_name and pwd == db_pwd:
 64                         print(‘登录成功‘)
 65                         user_info = [db_name, db_balance]
 66                         print(‘当前用户信息：‘, user_info)
 67                         tag = False
 68                         break
 69                 else:
 70                     print(‘用户名或密码错误‘)
 71                     count += 1
 72 
 73 
 74     elif choice == ‘3‘:
 75         print(‘shopping‘)
 76         if len(user_info) == 0:
 77             print(‘请先登录，谢谢‘)
 78         else:
 79 
 80             # 打印当前登录用户信息
 81             db_name = user_info[0]
 82             db_balance = user_info[1]
 83             print(‘用户信息‘.center(50, ‘-‘))
 84             print(‘‘‘尊敬的用户 %s 
 85 您的可用余额为 %s 元
 86                     ‘‘‘ % (db_name, db_balance))
 87             print(‘祝您购物愉快‘.center(50, ‘-‘))
 88             tag = True
 89             while tag:
 90 
 91                 # 循环打印带有索引的购物清单
 92                 for k, v in enumerate(product_list):
 93                     print(k, v)
 94                 choice = input(‘选择商品编号或按(q)退出>>:‘).strip()
 95                 if choice.isdigit():
 96                     choice = int(choice)
 97                     if choice < 1 or choice > 6:  # 判断用户的选择是否在索引范围之内
 98                         print(‘没有该商品，请重试‘)
 99                         continue
100 
101                     # 取出商品信息进行判断
102                     goods_name = product_list[choice][0]
103                     goods_price = product_list[choice][1]
104 
105                     if db_balance > goods_price:  # 余额大于商品价格时购买
106 
107                         if goods_name in shopping_cart:
108                             shopping_cart[goods_name][‘count‘] += 1  # 商品已存在时购物车内的商品个数加一
109                         else:
110                             shopping_cart[goods_name] = {‘price‘: goods_price, ‘count‘: 1}  # 不存在新加商品
111 
112                         db_balance -= goods_price
113                         user_info[1] = db_balance  # 用户每选择一个商品后将余额更新一次
114                     else:
115                         print(‘余额不足‘)
116                     print(shopping_cart)
117 
118                 elif choice == ‘q‘:
119                     print(shopping_cart)
120                     while tag:
121                         buy = input(‘确认购买商品吗(y/n)>>:‘).strip()
122                         if buy == ‘Y‘ or buy == ‘y‘:
123                             old_file = DB
124                             new_file = r‘%s.swap‘ % DB  # 购买之后写入文件
125                             with open(old_file, ‘r‘, encoding=‘utf-8‘) as read_f, 126                                     open(new_file, ‘w‘, encoding=‘utf-8‘) as write_f:
127                                 for line in read_f:
128                                     if line.startswith(db_name):
129                                         l = line.strip(‘
‘).split(‘|‘)  # 将字符串切成列表
130                                         l[-1] = str(db_balance)  # 修改余额
131                                         line = ‘|‘.join(l) + ‘
‘  # 重新拼回字符串
132 
133                                     write_f.write(line)
134                             os.remove(old_file)
135                             os.rename(new_file, old_file)
136 
137                             print(‘购买成功‘)
138 
139                         shopping_cart = {}
140                         user_info = []
141                         tag = False
142 
143                 else:
144                     print(‘输入错误，重试‘)
145 
146     else:
147         print(‘输入错误，请重试‘)

View Code

 

 

装饰器（用户登录认证） 

def login_auth(func):
    def wrapper(*args, **kwargs):
        ‘‘‘
        :param args:
        :param kwargs:
        :return:
        ‘‘‘
        return func(*args, **kwargs)

    return wrapper

View Code

单例模式的实现

#settings.py

IP=‘1.1.1.2‘
PORT=3302

 1 # 一：在内部定义一个类
 2 import settings
 3 
 4 
 5 class mysql:
 6     __instance = None
 7 
 8     def __init__(self, ip, port):
 9         self.ip = ip
10         self.port = port
11 
12     @classmethod
13     def conf(cls):
14         if cls.__instance is None:
15             cls.__instance = cls(settings.IP, settings.PORT)
16         return cls.__instance
17 
18 
19 obj = Mysql.conf()
20 obj1 = Mysql.conf()
21 obj2 = Mysql.conf()
22 print(obj)
23 print(obj1)
24 print(obj2)

方式一

 1 # 二：用装饰器
 2 import settings
 3 
 4 
 5 def singleton(cls):
 6     cls.__instance = cls(settings.IP, settings.PORT)
 7 
 8     def wrapper(*args, **kwargs):
 9         if len(args) == 0 and len(kwargs) == 0:
10             return cls.__instance
11         return cls(*args, **kwargs)
12 
13     return wrapper
14 
15 
16 @singleton
17 class Mysql:
18     def __init__(self, ip, port):
19         self.ip = ip
20         self.port = port
21 
22 
23 obj = Mysql()
24 obj1 = Mysql()
25 print(obj)
26 print(obj1)

方式二

 1 # 三：元类
 2 import settings
 3 
 4 
 5 class Mymeta(type):
 6     def __init__(self, class_name, class_bases, class_dic):
 7         super(Mymeta, self).__init__(class_name, class_bases, class_dic)
 8         self.__instance = self.__new__(self)
 9         self.__init__(self, settings.IP, settings.PORT)
10 
11     def __call__(self, *args, **kwargs):
12         if len(args) == 0 and len(kwargs) == 0:
13             return self.__instance
14 
15         obj = self.__new__(self)
16         self.__init__(obj, *args, **kwargs)
17         return obj
18 
19 
20 class Mysql(object, metaclass=Mymeta):
21     def __init__(self, ip, port):
22         self.ip = ip
23         self.port = port
24 
25 
26 obj = Mysql()
27 obj1 = Mysql()
28 print(obj)
29 print(obj1)

方式三

进度条 

 1 def grogress_bar(percent, width):
 2     if percent > 1: percent = 1
 3     show_str = (‘%%-%ds‘ % width) % (int(percent * width) * ‘#‘)
 4     print(‘
%s%% %s‘ % (int(percent * 100), show_str), end=‘‘)
 5 
 6 
 7 total_size = 123451
 8 recv_size = 0
 9 while total_size > recv_size:
10     time.sleep(0.2)
11     recv_size += 1024
12     percent = recv_size / total_size
13     grogress_bar(percent, width=40)

模拟文件的下载过程

 随机码

1 def hatted_code(n):
2     res=‘‘
3     for i in range(n):
4         num=str(random.randint(0,9))
5         alp=chr(random.randint(65,90))
6         res+=random.choice([num,alp])
7     return res
8 print(hatted_code(4))

随机四位数字字母组合的随机码