Python：匹配用户名和密码；如果错误则提示输入密码；

Question

我正在尝试创建一个登录功能。

我不太确定怎么创建或导入一个包含用户名和密码的库；我现在正在研究这个问题，但还是想问问。

要把用户名和密码匹配起来（这个部分已经解决了一些；需要添加多个用户名和对应的密码）。
如果密码错误，怎么创建一个循环？如果输入了错误的密码，用户需要再次被提示输入密码。

怎么限制密码输入的尝试次数。

下面是我尝试过的：

def check_password(user, password):
    """ Return True if the user/pass combo is valid and False otherwise. """

    # Code to lookup users and passwords goes here.  Since the question
    # was only about how to do a while loop, we have hardcoded usernames
    # and passwords.
    return user == "pi" and password == "123"

def login():
    """ Prompt for username and password, repeatedly until it works.
    Return True only if successful.
    """

    try:
        while True:
            username = raw_input('username:')
            password = raw_input('password:')
            if check_password(username, password):
                break
            else:
                print "Please try again"

        print "Access granted"
        return True
    except:
        return False

用于测试的：login()。

这个修复了如果密码错误时没有循环提示的问题，因为我用了return而不是print；用了if而不是while。

def login():
    #create login that knows all available user names and match to password ; if password is incorect returns try again and propmts for password again# 
    username = raw_input('username:')
    if username !='pi':
        #here is where I would need to import library of users and only accept those usernames; needs to be like 'pi' or 'bob' or 'tim'etc.
        print'user not found'
        username = raw_input('username')
    password = raw_input('password:')
    #how to match password with user? store in library ? 
    while password != '123':
        print 'please try again' # You have to change the 'return' to 'print' here
        password = raw_input('password')        
    return 'access granted'
    #basically need to create loop saying 'try again' and prompting for password again; maybe smarter to ask limited number of
    #times before returning 'you have reached limit of attempts#
    if password == '123':
        #again matching of passwords and users is required somehow 
        return 'access granted'

>>> login()
username:wronguser
user not found
usernamepi
password:wrongpass
please try again
password123
'access granted'
>>>

在更新之前的第一次尝试，感谢Merigrim的帮助：

def login():

    # Create login that knows all available user names and match to password;
    # if password is incorect returns try again and propmts for password again# 
    username = raw_input('username:')
    if username !='pi':
        # Here is where I would need to import library of users and only 
        # accept those usernames; needs to be like 'pi' or 'bob' or 'tim'etc.
        return 'user not found'

    password = raw_input('password:')

    # How to match password with user? store in library? 
    if password != '123':
        return 'please try again'
    
    password = raw_input('password:')
    if password != '123':
        return 'please try again'

    # Basically need to create loop saying 'try again' and prompting 
    # for password again; maybe smarter to ask limited number of
    # times before returning 'you have reached limit of attempts

    elif password == '123':
        # Again matching of passwords and users is required somehow 
        return 'access granted'

现在的工作方式是这样的：

>>> login()
username:pi
password:123
'access granted'
>>> login()
username:pi
password:wrongpass
'please try again'

我需要创建一个循环来再次提示输入密码。

代码调试用户身份验证库导入错误提示登录功能输入循环用户名密码匹配密码尝试限制

Python：匹配用户名和密码；如果错误则提示输入密码；

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