第三周day02作业

import time
import os

# 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
# 方式一：一次性读完修改完再覆盖原文件
# def file_modify(path,old,new):
#     '''文件修改'''
#     with open(r'{}'.format(path),'r',encoding='utf-8') as f:
#         res = f.read()
#         data = res.replace(old,new)
#     with open(r'{}'.format(path),'w',encoding='utf-8') as f1:
#         f1.write(data)
# file_modify(r'test.txt','alex','dsb')
# 方式二：以读的方式打开原文件,以写的方式打开一个临时文件,一行行读取原文件内容,修改完后写入临时文件,删掉原文件,将临时文件重命名原文件名
def file_modify(path,old,new):
    '''文件修改'''
    with open(r'{}'.format(path),'r',encoding='utf-8') as f,\
            open(r'.{}.swap'.format(path),'w',encoding='utf-8') as f1:
        for line in f:
            f1.write(line.replace(old,new))
    os.remove(r'{}'.format(path))
    os.rename(r'.{}.swap'.format(path),r'{}'.format(path))

# file_modify(r'test.txt','alex','dsb')



# 2、编写tail工具
# 需要新建一个py文件执行文件追加内容的操作
# 该文件打开的路径应该与输入的路径一致
# with open('test.txt','a',encoding='utf-8') as f:
#     f.write('哈哈哈\n')
def tail_tool():
    '''tail工具'''
    file_path = input('请输入要监听的文件路径：')
    with open('{}'.format(file_path),'rb') as f:
        f.seek(0,2)
        while True:
            line = f.readline()
            if line:
                print(line.decode('utf-8'),end='')
            else:
                time.sleep(0.5)
# tail_tool()
# 3、编写登录功能
# 需提前创建好user_info.txt
def login():
    '''登录功能'''
    print('欢迎来到登录界面'.center(30, '*'))
    user = input('请输入用户名：')
    with open(r'user_info.txt','r',encoding='utf-8') as f:
        if not f.read():
            print('用户文件中现在没有任何用户存在，请先注册')
        else:
            f.seek(0,0)
            for line in f:
                username,password = line.strip().split(':')
                if user in username:
                    pwd = input('请输入密码：')
                    if pwd == password:
                        print('登录成功')
                        break
                    else:
                        print('密码错误')
            else:
                print('该用户不存在')
# login()

# 4、编写注册功能
# 需提前创建好user_info.txt
def register():
    '''注册功能'''
    print('欢迎来到注册界面'.center(30, '*'))
    user = input('请输入用户名：')
    pwd = input('请输入密码')
    with open(r'user_info.txt','r+',encoding='utf-8') as f1:
        if not f1.read():
            f1.write('{}:{}\n'.format(user,pwd))
            print('注册成功')
        else:
            f1.seek(0,0)
            for line in f1:
                username,password = line.strip().split(':')
                if user in username:
                    print('该用户名存在，请重新注册')
                    break
            else:
                f1.write('{}:{}\n'.format(user,pwd))
                print('注册成功')
# register()