跟文件结合的验证登录

def login(username,password):
    f = open("db","r",encoding="utf-8")
    for line in f:
        line = line.strip()#默认strip无参数：移除空格换行符；有参数：移除两侧指定的值
        line_list = line.split("$$")
        if user == line_list[0] and pwd == line_list[1]:
            return True
    return False
def register(username,password):
    #注册用户
#1打开文件2用户名密码
    with open("db","a",encoding="utf-8") as f:
        temp = "\n" + username + "$$" + password
        f.write(temp)
def user_exist(username):
    #一行一行查找，如果用户名存在，returnTrue；False
    with open("db","r",encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            line_list = line.split("$$")
            if line_list[0] == username:
                return True
    return False
print("欢迎来到德莱联盟")
inp = input("1:登录；2:注册")
if inp == "1":
    user = input("请输入用户名:")
    pwd = input("请输入密码:")
    is_login = login(user,pwd)
    if is_login:
        print("登录成功")
    else:
        print("登录失败")
elif inp == "2":
    user = input("请输入用户：")
    pwd = input("请输入密码：")
    is_exist = user_exist(user)
    if is_exist:
        print("用户已存在，无法注册")
    else:
        register(user,pwd)
        print("注册成功")