python - 在 Python 中验证文本文件中的用户名和密码

Question

虽然我已经潜伏多年，但还是第一次发帖

我目前正在开发一个编程项目，但遇到了困难。该项目的目标是获取用户的输入、用户名和密码，并通过文本文件进行验证以查看其是否正确。如果正确，它将打印“欢迎!”并结束，如果没有，它将要求输入用户名和密码并循环，直到输入正确的组合。

文本文件采用以下格式:

Darth:Vader

Boba:Fett

R2:D2

ObiWan:Kenobi

Luke:Skywalker

这是我的代码:

# Lets user know what this program will do
print("Please login");

# Opens accounts txt file
accounts_file = open("accounts.txt", "r")

# Flag to terminate while loop
complete = False
# Runs loop until username and password are correct
while complete == False:
    # Asks user for username and stores as variable
    usernameInput = input("Username:");
    # Asks user for password and stores as variable
    passwordInput = input("Password:");
    # Reads each line of the text file line by line
    # Darth:Vader
    # Luke:Skywalker
    # R2:D2
    # ObiWan:Kenobi
    # Boba:Fett
    for line in accounts_file:
        # Stores each line in file as a username/password combo
        username, password = line.replace("\n","").split(":")
        # If username and password match, breaks out of the loop and sets complete to  True
        if usernameInput == username and passwordInput == password:
            complete = True
            break
        # Sets complete to False and loops back    
        else:
            complete = False
            continue
if complete == True:
    print("Welcome!");

如果第一次输入正确的名称，我可以让它正确运行: 例如:

Please login:

Username:Darth

Password:Vader

Welcome!

• ends program

如果我输入错误的名称，它会像这样循环:

Please login:

Username:Darth

Password:Fett

Username:.....

但是，如果我输入错误的用户名然后正确的用户名，它不会像我想要的那样结束程序，并继续循环:示例:

Please login:

Username:Luke Password:Vader

Username:Darth Password:Vader

Username:R2 Password:D2

知道是什么导致它不接受用户的下一个输入并完成循环吗？

感谢您的帮助!

Answer 1

这样做是因为您的文件在您第二次尝试读取时为空。

第一次运行整个文件后:

for line in accounts_file:
        # Stores each line in file as a username/password combo
        username, password = line.replace("\n","").split(":")
        # If username and password match, breaks out of the loop and sets complete to  True
        if usernameInput == username and passwordInput == password:
            complete = True
            break
        # Sets complete to False and loops back    
        else:
            complete = False
            continue

文件为空，即所谓的“已耗尽”。 如果用户错了，您每次都需要重新创建一个新的文件对象。就这样做:

accounts_file = open("accounts.txt", "r")
for line in accounts_file:
        # Stores each line in file as a username/password combo
        username, password = line.replace("\n","").split(":")
        # If username and password match, breaks out of the loop and sets complete to  True
        if usernameInput == username and passwordInput == password:
            complete = True
            break
        # Sets complete to False and loops back    
        else:
            complete = False
            continue
account_file.close() # Very important to close the file for next time!

或者你可以使用 with ... as ... 像这样:

with open("accounts.txt", "r") as accounts_file:
    for line in accounts_file:
        # Stores each line in file as a username/password combo
        username, password = line.replace("\n","").split(":")
        # If username and password match, breaks out of the loop and sets complete to  True
        if usernameInput == username and passwordInput == password:
            complete = True
            break
        # Sets complete to False and loops back    
        else:
            complete = False
            continue