如何修复 Python 中的无限循环？

Question

我在Python做一个登录安全程序，这部分总是陷入死循环。如果您被锁定，它会一直说 'you have been locked out for 10 seconds' 并无限循环。我该如何解决这个问题？

tries=0
while finalusername!=username or  finalpassword!=password:
tries=tries+1
print "That incorrect. Try again."
print "You have", 5-tries, "tries left."
finalusername= raw_input ("Username:")
finalpassword= raw_input ("Password:") 
while tries>=4:
    print "You have been locked out for 10 seconds. Please call the administrator if this keeps happening."
    sleep (10.0)
    system ('CLS')
    finalusername!=username
    finalpassword!=password

Answer 1

简单，改变

  while tries>=4:

至

  if tries >= 4:

如果您遵循您的代码，当您进入第二个 while 循环时，变量 tries 的值永远不会改变，因此您将永远留在其中。如果将 while 更改为 if，将执行 if 语句的主体，然后继续循环。

Answer 2

您的第二个 while 循环在 tries 大于四时激活，但循环本身从不在 tries 上运行或包含任何其他退出条件。这就是为什么它变得无限。所以 tries 保持在四以上并且循环永远不会停止。

从你的代码来看，在我看来，在他们用完尝试后，他们会被锁定 10 秒，然后他们会重新开始？如果是这样，您希望像这样调整您的代码：

tries=0
while finalusername!=username or  finalpassword!=password:
    tries=tries+1
    print "That incorrect. Try again."
    print "You have", 5-tries, "tries left."
    finalusername= raw_input ("Username:")
    finalpassword= raw_input ("Password:") 
    if tries>=4:
        print "You have been locked out for 10 seconds. Please call the administrator if this keeps happening."
        sleep (10.0)
        system ('CLS')
        tries = 0 #Reset tries counter
        finalusername!=username #I don't think this part is required
        finalpassword!=password #I don't think this part is required

Answer 3

我认为你应该在睡眠后将尝试设置为 0，如果不需要则循环。睡眠后用户应该再次尝试 5 次。

import os
import time

tries=0
finalusername, finalpassword= 'a', 'a'
username, password = None, None


while True:
    finalusername= raw_input ("Username:")
    finalpassword= raw_input ("Password:") 
    if finalpassword == username and finalpassword == password:
        break
    tries=tries+1
    print "That incorrect. Try again."
    print "You have", 5-tries, "tries left."
    if tries>=5:
        print "You have been locked out for 10 seconds. Please call the administrator if this keeps happening."
        time.sleep (10.0)
        os.system('cls')
        tries = 0

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