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 amend(new,chu,zhang):

import os

with open('a.txt',mode='rt',encoding='utf-8')as f_read,\

open('a.txt.swap',mode='wt',encoding='utf-8')as f_write:

for line in f_read:

if 'b.txt' in line:

line = line.replace('chu','zhang')

f_write.write(line)

os.remove('a.txt')

os.rename('a.txt.swap','a.txt')

amend(r'E:/untitled/day07/a.txt','alex','SB')

2、编写tail工具

import time

with open(r"/untitled/day06/access.log", mode="rb") as f:

f.seek(0, 2) # 快速将指针移动到文件末尾

while True:

line = f.readline()

if len(line) == 0:

time.sleep(0.1)

else:

print(line.decode('utf-8'),end='')

3、编写登录功能

def login():

count = 1

while count < 3:

inp_name = input('your name:').strip()

inp_pwd = input('your pwd:').strip()

with open('a.txt', mode='rt', encoding='utf-8')as f:

for line in f:

name, pwd = line.strip('\n').split('😂

if inp_name == name and inp_pwd == pwd:

print('login successful')

count = 6

break

else:

print('user or password error')

count + 1

login()

4、编写注册功能

def register():

user_name = input('your user_name:').strip()

user_pwd = input('your user_pwd:').strip()

with open('a.txt',mode='at',encoding='utf-8')as f1:

f1.write('%s:%s\n'%(user_name,user_pwd))

register()

5、编写用户认证功能

def auth():

with open('a.txt',mode='rt',encoding='utf-8')as f:

for line in f:

name, pwd = line.strip('\n').split('😂

if user_name == name and user_pwd == pwd:

return '认证成功'

user_name = input('your name:').strip()

user_pwd = input('your pwd:').strip()

res=auth()

print(res)

选做题：编写ATM程序实现下述功能，数据来源于文件db.txt

1、充值功能：用户输入充值钱数，db.txt中该账号钱数完成修改

2、转账功能：用户A向用户B转账1000元，db.txt中完成用户A账号减钱，用户B账号加钱

3、提现功能：用户输入提现金额，db.txt中该账号钱数减少

4、查询余额功能：输入账号查询余额

选做题中的选做题：登录功能

用户登录成功后，内存中记录下该状态，上述功能以当前登录状态为准，必须先登录才能操作