创建一个简单的登录系统作为个人项目并在 python 中遇到一些 IO 问题

Question

My question is that I am creating a login system in python. This system is very simple. The user type login , his email and password. The program checks from a file whether the email or password is correct or not. But I am running into some issues with that. So I first opened the file then asked the user if he wants to log in or signup. If he types login the program asks for email and password and check in the file whether this matches or not. The program takes input correctly but at the time of checking it fails. It does not give an error but it does not print the desired statement. This my code

with open('Data_Login_System.txt' , 'r') as data:
    user_input = input("""Type Either Login or SignUp> """)
    if user_input.lower() == "login":
        Email = input("""Type your Email> """)
        Password = input("""Type Your Password> """)
        for line in data:
           if line.lower() == f"email : {Email.lower()}" or line.lower() == f"password : {Password.lower()}":
               print("Logged in")

These are the contents of the file.

Email : shabeebasghar123@gmail.com
Password : shabeebasghar123

Whenever I enter the correct email and password it should print logged in but it does not the program just run finely and nothing at the end This is the execution of the program

Type Either Login or SignUp
> login
Type your Email
> shabeebasghar123@gmail.com
Type Your Password
> shabeebasghar123

Answer 1

它的工作line.lower().strip()是只执行line.lower().strip()而line.lower()

Answer 2

First of all you got to use a readlines() function to read lines from the .txt file with a loop. You could actually read a lines without a loop on that one. See code below.

lines = data.readlines()
print(data)

The out put for that would be: ['Email : mail@gmail.com\\n', 'Password : passwd123'].

So I would try a bit different approach. Make sure that you don't have any unwanted extra lines in txt file.

user_input = input("Type Either Login or SignUp")
if user_input.lower() == "login":
    email = input("""Type your Email""")
    password = input("""Type Your Password""")

    with open("data.txt", 'r') as f:
        t_mail = f.readline()
        t_passwd = f.readline()
        if f"Email : {email}\n" == t_mail and f"Password : {password}" == t_passwd:
            print('You are now logged in')

This works fine for me.