如何修复Python中的无限循环？

Question

我正在用Python开发一个登录安全程序，而这部分总是陷入无限循环中。 如果您被锁定，它会一直说“您已被锁定10秒钟”，并且无限循环。 我该如何解决？

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

容易，改变

  while tries>=4:

至

  if tries >= 4:

如果你按照你的代码，当你进入你的第二个while循环，变量的尝试值不会改变，所以你会留在了那里所有的永恒。 如果将while更改为if，则将执行if语句的主体，然后继续循环。

Answer 2

当tries大于4时，您的第二个while循环会激活，但是循环本身永远不会对tries或包含任何其他退出条件。 这就是为什么它变得无限大的原因。 因此tries保持在4以上，循环永远不会停止。

从您的代码看来，在他们用尽尝试之后，他们被锁定了10秒钟，然后又可以重新开始了？ 如果是这样，您希望像这样调整代码：

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

我认为您应该在睡眠后将try设置为0，并在不需要时进行循环。 睡眠后，用户应再次尝试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