Login System - Python - python-3.9

Question

I'm not that great at programming and so that is why I am here asking help. I am creating a login system for my Hotel Booking System but I am experiencing some problems with it.
This is what I have done for the Login Sytem through the help someone else's code. Link: Python Login and Register System using text files
def get_existing_users():
with open("login.txt", "r" ) as f:
for line in f.readlines():
# This expects each line of a file to be (name, pass) seperated by whitespace
username, password = line.split(',')
yield username, password
def is_authorized(username, password):
return any((user == (username, password) for user in get_existing_users()))
def user_exists(username):
return any((usr_name == username) for usr_name, _ in get_existing_users())
# above is equivalent of:
#
# for usr_name, _ in get_existing_users():
# if usr_name == username:
# return True
# return False
def ask_user_credentials():
count = 0
while count < 3:
username = input("Enter Username: ")
password = input("Enter a Password: ")
if is_authorized(username, password):
print ("Welcome to the Majestic Hotel Booking system ") + username
MainMenu()
if user_exists(username):
print("The password entered is wrong, please try again")
print("The username entered is wrong, please try again")
count = count + 1
def getdetails():
forename = input("Enter forename: ")
surname = input("Enter Surname: ")
year = input("Enter year you are born: ")
if year <= '2004':
print("You are old enough to register yourself")
username = forename[0]+surname[0:3]+year[3:4]
print("Username: ", username)
password = input("Enter a password: ")
file = open("login.txt","a")
file.write(username + "," + password + "\n")
file.close()
MainMenu()
else:
print("Sorry you are not old enough to register by yourself") enter code here
if account == "No":
print(getdetails())
if account == "Yes":
print(ask_user_credentials())
After creating or logging in to the account, the program will direct them to the main menu that is why you will see MainMenu() in the code.
I created an account, as shown below:
WELCOME TO THE MAJESTIC HOTEL lOGIN SYSTEM
************************************************
Do you have an account? Yes or No: No
Enter forename: Rose
Enter Surname: Moon
Enter year you are born: 2000
You are old enough to register yourself
Username: RMoo0
Enter a password: door
This was then saved in a text file called login.txt, like this:
RMoo0,door
However, although I created an account and it is saved into the text file but the output says this:
WELCOME TO THE MAJESTIC HOTEL lOGIN SYSTEM
************************************************
Do you have an account? Yes or No: Yes
Enter Username: RMoo0
Enter a Password: door
The password entered is wrong, please try again
The username entered is wrong, please try again
Enter Username:
Can someone please help me out and explain the solution in a way that I will understand it.

Answer 1

f.readlines() gives each line of txt file as :
line1\n
line2\n
.
.
.
So ,when you try to get username, password by split(",") , it look like this
("user1", "password1\n")
("user2", "password2\n")
..
Before splitting line with "," right strip each line with rstrip("\n")
def get_existing_users():
with open("login.txt", "r" ) as f:
for line in f.readlines():
username, password = line.rstrip("\n").split(',') #used rstrip here to remove the right ending "\n"
yield username, password

Answer 2

When addressing this kind of problem your should take into account several aspects like for example escaping your separators (of course, if you hash your passwords this isn't necessary) and not utilizing white spaces, a very good approach like linux passwd file is to add separator at the end of line to avoid different EOL terminators like \r, \n or \r\n
for Example:
def get_existing_users():
"""
This expects each line of a file to be:
(start of line)name,pass,(end of line)
"""
with open("login.txt", "r" ) as f:
for line in f.readlines():
user = line.split(',')
yield user[0], user[1]