8.15 课后作业

1. 给定验证码长度n，生成随机验证码，验证码由数字、字母组成（参考chr()内置方法）

   import random
   
   def yanzhengma(n):
       for i in range(n):
           s = random.randint(1, 3)
           if s == 1:
               print(chr(random.randint(48, 57)), end='')
           if s == 2:
               print(chr(random.randint(65, 90)), end='')
           if s == 3:
               print(chr(random.randint(97, 122)), end='')
   yanzhengma(10)

2. 打印进度条

   import time
   
   def line(n):
       start = time.perf_counter()
       for i in range(n + 1):
           # （f'\r{},end=''）实现单行刷新字符串，依次覆盖前面的字符串
           print(f'\r{((i / n) * 100): ^3.1f}%[{"#" * i}->{"." * (n - 1 - i)}]  {time.perf_counter() - start:.2f}s',end='')
           time.sleep(0.1)
   line(int(input("输入一个整数：")))