文本操作

1）打开两个文件并执行操作
with open('文件操作','r',encoding= 'utf-8') as f,open('文件操作.bak','w',encoding= 'utf-8') as f2:

    for line in f:
        if 'star' in line:
            line = line.replace('star','杏儿')

        f2.write(line)

import os
os.remove('文件操作')
os.rename('文件操作.bak','文件操作')

2）设置3次机会登陆

username = input('请输入用户名')
while 1:
    psd1 = input('请输入密码')
    psd2 = input('请确认密码')
    if psd1 == psd2:
        break
    else:
        print('两次密码不一致，请重新确认')
with open('test','w',encoding = 'utf-8') as f:
    f.write('{}\n{}'.format(username,psd1))
print('注册成功')
lst = []
i = 1
while i < 4:
    with open('test', 'r', encoding='utf-8') as f1:
        for line in f1:
            lst.append(line.strip())


    user = input('请输入用户名或输入Q退出')
    if user.strip().upper() == 'Q':
        break
    elif user == lst[0]:
        psd = input('请输入密码')
        if psd == lst[1]:
            print('登陆成功')
            break
        else:
            print('密码错误，请重新输入,你还有{}次机会'.format(3-i))
            i += 1

    else:
        if i == 3:
            print('已经没有机会了')
        else:
            print('用户名错误，请重新输入,你还有{}次机会'.format(3-i))
        i += 1