Python学习笔记（十）：
- 装饰器的应用
- 列表生成式
- 生成器
- 迭代器
- 模块：time,random
1. 装饰器的应用-登陆练习
login_status = False # 定义登陆状态def type(auth_type): # 装饰器传参函数 def login(fucn): # 装饰器函数 def inner(): # 附加功能 global login_status # 将登陆状态变量变为全局变量 if login_status == False: if auth_type == 'jingdong': username = input('username:') password = input('password:') with open('jingdong.txt','r') as f: lines = f.readlines() for i in lines: i = eval(i) if username in i and password == i[username]: print('welcome %s' % (username)) login_status = True fucn() else: print('wrong username or password') elif auth_type == 'weixin': username = input('username:') password = input('password:') with open('weixin.txt', 'r') as f: lines = f.readlines() for i in lines: i = eval(i) if username in i and password == i[username]: print('welcome %s' % (username)) login_status = True fucn() else: print('wrong username or password') else: pass return inner return login@type('jingdong') # 连接装饰器def home(): # 功能函数 print('welcome to home page')@type('weixin')def finance(): print('welcome to finance page')@type('jingdong')def book(): print('welcome to book page')if __name__ == '__main__': while True: print('welcome to JD:') print('choice 1 to home') print('choice 2 to finance') print('choice 3 to book') print('choice 0 to back') choice = input('Where are you going:') if choice == '1': home() elif choice == '2': finance() elif choice == '3': book() elif choice == '0': break 2. 列表生成式
代码示例：
a = [x for x in range(10)]print(a) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]a = [x*2 for x in range(10)]print(a) # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]def f(n): return n**3a = [f(x) for x in range(10)]print(a) # [0, 1, 8, 27, 64, 125, 216, 343, 512, 729]
3. 生成器
代码示例：
# 第一种方法s = (x for x in range(100)) # 生成器# for的作用：消除内存占用，判断遍历完成for i in s: print(i)# 第二种方法def foo(): i = range(22) yield ifor i in foo(): print(i)# send方法给yield赋值def bar(): print('ok1') count = yield 1 # 接收'ee' print(count) print('ok2') yield 2b = bar()b.send(None) # 相当于next(b)b.send('ee') # 将'ee'赋值给第一个yield 4. 迭代器
- 生成器都是迭代器 什么是迭代器？
- 有iter方法
- 有next方法
5. 模块
1. time模块
函数/方法：
time() -- return current time in seconds since the Epoch as a float clock() -- return CPU time since process start as a float sleep() -- delay for a number of seconds given as a float gmtime() -- convert seconds since Epoch to UTC tuple localtime() -- convert seconds since Epoch to local time tuple asctime() -- convert time tuple to string ctime() -- convert time in seconds to string mktime() -- convert local time tuple to seconds since Epoch strftime() -- convert time tuple to string according to format specification strptime() -- parse string to time tuple according to format specification tzset() -- change the local timezone代码示例：
print(time.strftime('%Y-%m-%d %H:%M:%S')) #2017-09-20 13:44:01print(time.strptime('2017-09-20 12:53:21','%Y-%m-%d %H:%M:%S'))# time.struct_time(tm_year=2017, tm_mon=9, tm_mday=20, tm_hour=12, tm_min=53, tm_sec=21, tm_wday=2, tm_yday=263, tm_isdst=-1) 2. random模块
print(random.randint(1,8)) # 从1-8中随机取值print(random.choice('hello')) # 从‘hello’中随机取一个字母# 实现验证码def v_code(): code = '' for i in range(5): add = random.choice([random.randrange(10),chr(random.randrange(65,91))]) code += str(add) print(code)v_code()