# 帐户表account： # sylar:123 # alex:456 # wusir:789 # taibai:789 # 需熟练的知识点：文件操作with open()/write()/read()、去掉所有空格strip()、切割split()、所有字母大写upper() # 循环for...in...、判断if...else...

def regist():     # 输入数据     # 用户名若存在则不通过：注册失败     # 通过则存入account: mode="r+"     print("请输入用户名及密码完成注册")     username = input("请输入注册用户名：")     password = input("请输入密码")     with open("account", mode="r+", encoding="utf-8") as f:         for line in f:            # sylar:123             if username == line.strip().split(":")[0]:                 print("对不起，该用户已注册")                 break         else:             f.write("\n"+username+":"+password)             print("注册名为：%s" % username)             print("注册的密码为：%s" % password) regist() def login():     count = 3     while count > 0:           count -= 1           username = input("请输入用户名：").strip()           password = input("请输入密码：").strip()           with open("account", mode="r", encoding="utf-8") as f:                 for item in f:                    if username +":"+password == item.strip():                        return True                else:                     print("密码错误，您还有%s 次机会" % count)     return "程序退出" while 1:     print("注册: 1 登录: 2 退出: Q")     num = input("请输入:").strip()     if num.upper() == "Q":         break     elif num == "1":         regist()     elif num == "2":         if login():             print("登录成功!")             break         else:             print("登录失败!")     else:         print("输入错误! 重新输入!")