小程序1：登录/注册小程序

注册

account_lst = []
flag = True
with open("user.txt",mode='r+',encoding='utf-8') as fp:
    while flag:
        username = input("请输入用户名:")
        if username == "" or " " in username:
            print("您输入的用户名非法")
        else:
            fp.seek(0)
            lst = fp.readlines()
            for i in lst:
                account = i.strip().split(":")[0]
                account_lst.append(account)

                if username in account_lst:
                    print("用户名已经存在")
                else:
                    pwd = input("请输入密码")
                    while True:
                        pwd2 = input("请再次输入密码")
                        if pwd == pwd2:
                            strvar = username + ":" + pwd + "
"
                            fp.write(strvar)
                            flag = False
                            print("注册成功")
                            break
                        elif pwd2 == 'q'
                            break
                        else:
                            print("两次密码输入不一致")

登录

# ### 登录
    # 1.账户密码会预先记录在文件中
    # 2.输入账号密码:如果都正确,登录成功
    # 3.如果用户登录时进行三次校验,都不对,记录黑名单文件中
    # 4.如果是黑名单的用户,禁止下次再次登录

# 存账户
accountlst = []
# 存密码
pwdlst = []
# 存黑名单
blacklst = []

sign = True
while sign:
    username = input("请输入您的用户名:")
    # 获取文件当中的账号和密码
    with open("user.txt",mode="a+",encoding="utf-8") as fp:
        fp.seek(0)
        lst = fp.readlines()
        for i in lst:
            user,pwd = i.strip().split(":")
            # print(username,password)
            accountlst.append(user)
            pwdlst.append(pwd)
            
        # print(accountlst)
        # print(pwdlst)
        # 判断该用户是否存在
        if username in accountlst:
            # 获取文件中的黑名单列表
            with open("black.txt",mode="a+",encoding="utf-8") as fp:
                fp.seek(0)
                lst = fp.readlines()
                for i in lst:
                    blacklst.append(i.strip())
            # 判断当前用户是否是黑名单中的用户
            if username in blacklst:
                print("抱歉,该用户已经被冻结了")
            else:
                # 如何找到该账户对应的密码呢?
                num = accountlst.index(username)
                pwd = pwdlst[num]
                # print(num,pwd)
                """"""
                # 判断用户输入的密码是否正确
                times = 1
                while times <= 3:
                    pwd2 = input("请输入您的密码")
                    # 输入成功情况下,终止循环,程序结束
                    if pwd == pwd2:
                        print("登录成功")
                        sign = False
                        break
                    else:
                        # 剩余的次数 = 总次数 - 使用次数
                        print("你还剩下%s次机会" % (3 - times))                    
                        
                        # 如果用掉了所有的次数,直接加入黑名单,防止下次登录
                        if times == 3:
                            with open("black.txt",mode="a+",encoding="utf-8") as fp:                        
                                strvar = username + "
"
                                fp.write(strvar)
                            print("抱歉,您的账户已经被冻结~")                
                    times += 1 
        else:
            print("该用户不存在~")
        

注册流程图

登录流程图