Question

你好我有这个登录，我正在尝试，当我到达命令屏幕，如果我想退出程序我键入“退出”，但问题是我有一个双时循环和不知道如何突破两者。以下是代码示例：

a = 0
b = 0
loginatt = 0

while a == 0:
    if loginatt == 4:
        print "Too many tires!"
        break
    password = raw_input("Password: ")
    if password == "test":
        b = 1
        while b == 1:
            command = raw_input("command: ")
            if command == "exit":
                break
    else:
        loginatt += 1
        print "error, login failed!"

这部分代码不会突破double while循环：

command = raw_input("command: ")
            if command == "exit":
                break

Answer 1

break只会留下一个级别的循环。您可以尝试重置外部循环变量：

if command == "exit":
   a = 1
   break

但是，最好稍微破解你的代码：

def access_control(correct_pass="test", attempts=4):
    """Control access to the supplied function func."""
    for _ in range(attempts):
        password = raw_input("Password: ")
        if password == correct_pass:
            get_commands()
            break
        else:
            print "Incorrect password."
    else:
        print "Too many tries."

def get_commands():
    """Take user input until they enter 'exit'."""
    while True:
        command = raw_input("Command: ")
        if command == "exit":
            break

您现在可以致电access_control输入密码;如果正确，您将被转移到get_commands：

>>> access_control()
Password: test
Command: exit
>>>

或

>>> access_control()
Password: foo
Incorrect password.
Password: bar
Incorrect password.
Password: baz
Incorrect password.
Password: python
Incorrect password.
Too many tries.
>>>

Answer 2

没有关键字可以从多个循环中断开。您可以尝试以下方法：

wantToBreak = False
while b == 1:
    command = raw_input("command: ")
    if command == "exit":
        wantToBreak = True
        break
if wantToBreak:
        break

它利用一个布尔变量来指示是否应该中断流程（打破更多级别）。

Answer 3

通常，a和b之类的变量名称不是非常明确的。此外，您的登录功能与您的命令功能无关，因此为什么不将它们分开？

#! /usr/bin/python2.7

def login(maxTries = 4):
    while maxTries:
        password = raw_input('Password: ')
        if password == 'test':
            return True
        maxTries -= 1
    print 'Too many tries.'
    return False

def runCommand():
    while True:
        command = raw_input('Command: ')
        if command == 'exit': break
        print 'processing command', command

if login(): runCommand()

在找到命令exit时，您也可以使用带有标记的迭代器，而不是断开：

def runCommand():
    for command in iter(lambda: raw_input('Command: '), 'exit'):
        print 'processing command', command

打破双重循环？

3 个答案: