Question

我正在尝试让我的代码要求输入密码并接收密码，如果密码是正确的，如果不会发生其他事情会发生某些事情，当我尝试我的代码时，它会在第10行和第18行给出错误：

if (password == 'xxxx'):
UnboundLocalError: local variable 'password' referenced before assignment

以下是代码：

import random

def askforPassword():
    print('Welcome to the Machine!')
    print('Enter the password: ')
    password = input()

def getPassword():
    while passwordTry != 0:
       if (password == 'xxxx'):
        print('Correct')
       else:
        passwordTry -= 1
        print('INCORRECT!')

passwordTry = 5
askforPassword()
getPassword()

Answer 1

既然你问为什么它不起作用，让我们来看看你得到的错误：

Traceback (most recent call last):
  File "pw.py", line 18, in <module>
    getPassword()
  File "pw.py", line 10, in getPassword
    if (password == 'xxxx'):
UnboundLocalError: local variable 'password' referenced before assignment

它的含义是您尝试访问本地变量'password'，而您尚未创建任何此类局部变量。

如果您想使用全局变量，请明确说明：

def getPassword():
    global password
    while passwordTry != 0:
       if (password == 'xxxx'):
        print('Correct')
       else:
        passwordTry -= 1
        print('INCORRECT!')

但这仍然行不通，因为没有人设置这个全局变量。您还需要更改askforPassword：

def askforPassword():
    global password
    print('Welcome to the Machine!')
    print('Enter the password: ')
    password = input()

这仍然存在很多问题。例如，你只需要调用askforPassword一次，而不是每次调用一次，所以它只需要询问一次，然后打印INCORRECT! 5次。此外，不使用全局变量 - 具有askforPassword return密码会更好，并将其存储在getPassword中的局部变量中。

def askforPassword():
    print('Welcome to the Machine!')
    print('Enter the password: ')
    password = input()
    return password

def getPassword():
    while passwordTry != 0:
       password = askforPassword()
       if (password == 'xxxx'):
        print('Correct')
       else:
        passwordTry -= 1
        print('INCORRECT!')

你可能也希望从getPassword返回一些东西，所以无论谁调用它都知道你是成功还是失败。

Answer 2

您可能想要将逻辑略微改为：

import random

def askforPassword():
    print('Welcome to the Machine!')
    print('Enter the password: ')
    password = input()
    return password

def getPassword():
    passwordTry = 5
    while passwordTry:
       if (askforPassword() == 'xxxx'):
            print('Correct')
            break
       else:
            passwordTry -= 1
            print('INCORRECT!')

getPassword()

Answer 3

import random
password=-1
passwordTry=5

def askforPassword():
    global password                    # define as global
    print('Welcome to the Machine!')
    print('Enter the password: ')
    password = raw_input()             # python < 3 ? use raw_input

def getPassword():
    global password                    # not func. local
    global passwordTry                 # not local, global
    while passwordTry != 0:
       askforPassword()                # ask in each iteration
       if (password == 'xxxx'): 
        print('Correct')
        break                          # don't ask if correct
       else:
        passwordTry -= 1               # not password, passwordTry
        print('INCORRECT!')

getPassword()

Answer 4

无论您最终做什么，而不是input()或raw_input()，请确保使用标准Python模块getpass（以便它不会回显到stdout）：< / p>

import getpass
foo = getpass.getpass('Enter the password: ')
print('You typed: %s'%foo)

在赋值错误之前引用变量

4 个答案: