3.17作业

# 1、编写文件修改功能，调用函数时，传入三个参数（修改的文件路径，要修改的内容，修改后的内容）既可完成文件的修改
# def fc (file,x,y):
#     with open(r'{}'.format(file),mode='rt',encoding="utf=-8")as f:
#         res=f.read()
#         data=res.replace(x,y)
#     with open(r'{}'.format(file),mode='wt',encoding="utf=-8")as f1:
#         f1.write(data)

# 2、编写tail工具
# def tail()
#     import time
#     with open('a.txt', mode='rb') as f:
#         f.seek(0,2)
#         while True:
#             line=f.readline()
#             if len(line) == 0:
#                 time.sleep(0.3)
#             else:
#                 print(line.decode('utf-8'),end='')



# 3、编写登录功能
# def login()
#     while True:
#         inp_name=input('请输入用户名：')
#         inp_pwd=input('请输入密码：')
#         with open('user.txt','r',encoding='utf-8')as f:
#             for line in f:
#                 username,password=line.strip().split(':')
#                 if inp_pwd==username and inp_pwd==password:
#                     print('登陆成功')
#                     break
#             else:
#                 print('登录失败')

# 4、编写注册功能
# def enrol()
#     res={}
#     while True:
#        with open('user.txt','r',encoding='utf-8')as f:
#             for line in f:
#                 username,password=line.strip().split(':')
#                 res[username]=password
#     while True:
#         inp_name = input('请输入用户名：')
#         if inp_name in res:
#             print('用户已存在')
#             continue
#         inp_pwd = input('请输入密码：')
#         re_inp_pwd = input('请输入密码：')
#         if inp_pwd==re_inp_pwd:
#             print('注册成功')
#             with open('user.txt','a',encoding='utf-8')as f2:
#                 f2.write('{}:{}
'.format(inp_name,inp_pwd))
#             break
#         else:
#             print('两次密码不一致')