如何修复Python中的无限循环？

Question

我用Python编写了一个登录安全程序，这个部分总是陷入无限循环。如果你被锁在外面，它会一直说“你已经被锁在外面10秒了”，它会无限循环。我怎么解决这个问题？在

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，换一下

  while tries>=4:

到

^{pr2}$

如果你遵循你的代码，当你进入第二个while循环时，变量的值永远不会改变，所以你将永远呆在那里。如果将while更改为If，则将执行If语句的主体，然后继续循环。在

Answer 2

当tries大于4时，第二个while循环激活，但循环本身从不对tries进行操作或包含任何其他退出条件。这就是为什么它变得无限。因此tries保持在4以上，循环从未停止。在

从你的代码来看，在我看来，当他们用尽了他们的尝试，他们会被锁定10秒，然后他们可以重新开始？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

我认为你应该在睡眠后将尝试设置为0，如果没有必要，可以设置循环。睡眠后，用户应再次尝试5次。在

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