我该如何修复while循环

Question

我正在编写一个程序，要求用户输入密码。 如果密码与我设置的常数匹配，则会打印出“成功登录消息”。 但是，如果密码不正确，则会给出剩余的猜测数，并要求用户重试。 该程序应该在3次错误的猜测之后结束，但是即使使用了3次尝试，它仍会继续询问。 我认为问题出在我的while循环中，但我不确定。

码：

def main():
    PASSWORD = "apple"
    ALLOWED = 3

    password = input("Enter the password: ")
    while password != PASSWORD :
        ALLOWED = ALLOWED - 1
        print("Wrong. You have", ALLOWED, "guesses left")

        if ALLOWED == 0:
                    print("You have been locked out")
        password = input("Enter again ")            


    print("You have successfully logged into the system")



main()

Answer 1

现在，您永远不会退出while循环。 要打破它，请使用break关键字。 要完全退出程序，您将需要import sys和sys.exit()我建议将它们添加到if ALLOWED == 0语句中。

Answer 2

您需要使用break退出循环，或添加一个辅助条件，否则它将继续进行直到密码正确为止。

因此，要么：

while (password != PASSWORD) and (ALLOWED > 0):

要么：

    if ALLOWED == 0:
                print("You have been locked out")
                break

Answer 3

条件密码！= PASSWORD不足以退出循环（只有输入正确的密码，它才会退出循环）。 同时在while中添加条件（密码！= PASSWORD，并且允许> 0）

Answer 4

将print("You have been locked out")更改为sys.exit("You have been locked out") （否则退出main ）。 记住要import sys以使用sys.exit 。

Answer 5

您的while循环需要输入正确的密码才能完成，并且没有其他方法可以退出循环。 我建议一个中断声明：

def main():
    PASSWORD = "apple"
    ALLOWED = 3

    password = input("Enter the password: ")
    while password != PASSWORD :
        ALLOWED = ALLOWED - 1
        print("Wrong. You have", ALLOWED, "guesses left")

        if ALLOWED == 0:
            print("You have been locked out")
            break
        password = input("Enter again ")

    print("You have successfully logged into the system")

如果您的程序需要安全，则可能需要做更多研究。

Answer 6

设法使其工作，但只是使其检查是否ALLOWED == 0，并且是否确实打印“您被锁定”，并且如果ALLOWED <= 0，则它不会让您走得更远。

def main():
    PASSWORD = "apple"
    ALLOWED = 3

    password = input("Enter the password: ")
    while password != PASSWORD or ALLOWED <= 0:
        ALLOWED = ALLOWED - 1
        if ALLOWED > 0: print("Wrong. You have", ALLOWED, "guesses left")
        if ALLOWED == 0: print("You have been locked out") 
        if ALLOWED < 0:
                    print("You have been locked out")
        password = input("Enter again ")            


    print("You have successfully logged into the system")



main()

还写了一个不同的版本，我认为这似乎更容易

def main():

    USERNAME = "admin"
    PASSWORD = "root"
    ATTEMPTS = 3
    while ATTEMPTS >= 1:
        print("You have",ATTEMPTS,"attempts left")
        if ATTEMPTS == 0:
            break
        user = input("Please enter your username:")
        password = input("Now enter your password:")
        if user == USERNAME and password == PASSWORD:
            print("\nYou have successfully logged into the system")
            return
        else:
            print("\nThis user name or password does not exist\n")
            ATTEMPTS -= 1
    print("you have been locked out.")

main()