This program works to check usernames and passwords to let a user in. However, at the end where I am adding a new user, I want the user to immediately be able to try to import their newly created username and password so they can enter the program, without re-running after their username and password are added to the database. However, this code is returning the error "list index is out of range"

STAGE 1: Opening the files and grabbing data

filename1 = "c:UsersAnna HamelinDocumentsPython ScriptsSourceCodeProject2usernames.txt"
file = open(filename1, "r")

#Usernames

users = file.read()

usernameslist = [line.strip() for line in open("c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\usernames.txt")]

#print(users)                #Check file

#print(usernameslist)       #Check usernames list

file.close()



filename2 = "c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\passwords.txt"

file = open(filename2, "r")



#Passwords

passwords = file.read()

passwordslist = [line.strip() for line in open("c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\passwords.txt")]

#print(passwords)            #Check file

#print(passwordslist)       #Check passwords list

file.close()



#Compile the usernames and passwords lists for easy checking

#compiled_list = list(zip(usernameslist,passwordslist))

#print(compiled_list)



#Scores

filename3 = "c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\scores.txt"

file = open(filename3, "r")



scores = file.read()

scoreslist = [line.strip() for line in open("c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\scores.txt")]

#print(scores)           #Check file

#print(scoreslist)       #Check scores

file.close()



#STAGE 2

#Print Welcome/Intro message



response = input("-"*50 + "nWelcome! Do you have an account (y/n)? ")

print("-"*50)



#If user has an account:

if response == "y":

    #Create a login function:

    #def login():

        goodlogin = False

        username = input("Please enter your username: ")

        password = input("Please enter your password: ")  

        for id in range(len(usernameslist)):

            if username == usernameslist[id] and password == passwordslist[id]:

                goodlogin = True 



        if goodlogin:

            print(print_in_green + "Access granted!" + print_default)

        else:

            print(print_in_red + "Incorrect Login credentials, please try again." + print_default)

    #login()



#If user does not have account:

else: 

    newusername = input("What is your new username? ")

    newpassowrd = input("What is your new password? ")

    file = open(filename1, "a")

    file.write("n" + newusername)

    file = open(filename2, "a")

    file.write("n" + newpassowrd)

    file.close

    print("Now that you have created an account, please continue.")

    goodlogin = False

    username = input("Please enter your username: ")

    password = input("Please enter your password: ")  

    for id in range(len(usernameslist)):

        if username == usernameslist[id] and password == passwordslist[id]:

                goodlogin = True 



    if goodlogin:

            print(print_in_green + "Access granted!" + print_default)

    else:

            print(print_in_red + "Incorrect Login credentials, please try again." + print_default)

You can abstract that interaction logic out into a loop. You can also remove a bunch of code with you use the with option of opening/closing files. Here's a prototype to keep users and passwords updated.

Your authentication is .... not safe haha, since multiple users can have the same password etc. I would create a hash out of the combination of the user and password, but thats a different story :)

def interact(user_names_ls, passwords_ls):

    goodlogin = False

    username = raw_input("Please enter your username: ")

    password = raw_input("Please enter your password: ")

    if username in user_names_ls and password in passwords_ls:

        goodlogin = True



    if goodlogin:

        print( "Access granted!")

    else:

        print("Incorrect Login credentials, please try again.")

        interact(user_names_ls, passwords_ls)





usernames_file_path = "usernames.txt"

with open(usernames_file_path, "r") as f:

    user_names_ls = f.readlines()

    user_names_ls = [user.rstrip() for user in user_names_ls]



passwords_file_path = "passwords.txt"

with open(passwords_file_path, "r") as f:

    passwords_ls = f.readlines()

    passwords_ls = [password.rstrip() for password in passwords_ls]





print("-"*50)

end_interaction = False



while not end_interaction:

    response = raw_input("-" * 50 + "nWelcome! Do you have an account (y/n) [q to quit]? ")



    if response == "q":

        end_interaction = True



    #If user has an account:

    if response == "y":

        interact(user_names_ls, passwords_ls)



    #If user does not have account:

    else:

        newusername = raw_input("What is your new username? ")

        newpassowrd = raw_input("What is your new password? ")



        # here's where we can update our user and password cache

        user_names_ls.append(newusername)

        passwords_ls.append(newpassowrd)



# officially update the 'databases'

with open(usernames_file_path, "w") as f:

    user_names_ls = f.writelines(user_names_ls)





with open(usernames_file_path, "w") as f:

    passwords_ls = f.writelines(passwords_ls)

Sample interaction:

Welcome! Do you have an account (y/n) [q to quit]? n

What is your new username? he

What is your new password? 99

--------------------------------------------------

Welcome! Do you have an account (y/n) [q to quit]? y

Please enter your username: he

Please enter your password: 99

Access granted!

--------------------------------------------------

Welcome! Do you have an account (y/n) [q to quit]? 

btw - I used raw_input here but you can just swap that with input

I added a couple of functions to reduce code reuse. Also I load the usernames and passwords in the login_user function so it always gets the latest copy.

users_path = "c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\usernames.txt"

passwords_path = "c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\passwords.txt"

scoreslist_path = "c:\Users\Anna Hamelin\Documents\Python Scripts\SourceCode\Project2\scores.txt"





def get_file_contents(file_path):

    return [line.strip() for line in open(file_path)]



scoreslist = get_file_contents(scoreslist_path)



def add_file_contents(file_path, contents):

    with open(file_path, "a") as file:

        file.write(contents)



def login_user(new_account=False):

    usernameslist = get_file_contents(users_path)

    passwordslist = get_file_contents(passwords_path)



    if new_account:

        response = 'y'

    else:

        response = input("-"*50 + "nWelcome! Do you have an account (y/n)? ")

        print("-"*50)



    #If user has an account:

    if response == "y":

            goodlogin = False

            username = input("Please enter your username: ")

            password = input("Please enter your password: ")

            for id in range(len(usernameslist)):

                if username == usernameslist[id] and password == passwordslist[id]:

                    goodlogin = True



            if goodlogin:

                print("Access granted!")

            else:

                print("Incorrect Login credentials, please try again.")



    #If user does not have account:

    else:

        newusername = input("What is your new username? ")

        newpassword = input("What is your new password? ")

        add_file_contents(users_path, 'n' + newusername)

        add_file_contents(passwords_path, 'n' + newpassword)

        login_user(new_account=True)



login_user()