Python 尽管输入了正确的信息，程序总是求助于“错误登录”

我看不到我的代码中有任何总是导致输出错误登录的缺陷

credentials = {
    "username1": "password1",
    "username2": "password2"
}
while True:
    useroutput = input("Type in your username: ")
    passoutput = input("Type in your password: ")
    if useroutput in credentials.keys() and not(passoutput in credentials.keys()) and passoutput in credentials:
        print("Welcome back "+useroutput+"!")
        break
    else:
        print("Wrong login!")
        continue

---

这将检查用户名是否已知，然后检查密码是否分配给用户名

credentials = {
    "username1": "password1",
    "username2": "password2"
}
while True:
    useroutput = input("Type in your username: ")
    passoutput = input("Type in your password: ")
    if useroutput in credentials:
        if credentials[useroutput] == passoutput:
            print("Welcome back "+useroutput+"!")
            break

    print("Wrong login!")

你的情况不起作用，因为这部分

not(passoutput in credentials.keys()) and passoutput in credentials

---

永远都是假的。凭证中的passoutput将签入密钥。我想您希望在credentials.values中使用passoutput。即使这个“会”起作用，每个用户都可以使用字典中的每个密码登录。

如果条件没有意义，那么我完全可以理解，请详细说明为什么不在凭据中同时使用notpassoutput.key和passoutput凭据？这自相矛盾。