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Append lines from a text file to a list in python without '\n'

I'm currently learning python and I have a login system that uses a text file called "users" to store the usernames. I want to be able to update this file by reading the text line by line and appending it to an array in python. Then writing the array back into the text file to be appended into the array again the next time I open the program.
But right now, as each username is written in different lines, when I append it to my array it gives me:username = ['testing1\n', 'testing2']
this is my code:
import random
import operator
import shelve
import os
from os import system, name
import time
from time import sleep
users = []
password = []
def clear():
if name == 'nt':
_ = system('cls')
else:
print("thisisweird.")
# start of login system
def loggedOut():
status = input("Are you a registered user? y/n? Press q to quit ")
if status == "y":
oldUser()
elif status == "n":
newUser()
elif status == "q":
quit()
def loggedIn():
menu()
def newUser():
createLogin = input('Create a Username: ')
if createLogin in users:
print("\nUsername is taken")
else:
users.append(createLogin)
createPwd = input("Create a Password: ")
password.append(createPwd)
print("\nRegister successful\n")
loggedOut()
def oldUser():
login = input("Enter username: ")
pwd = input("Enter password:")
if login in users and users[login] == pwd:
print("\nWelcome,", login,"!")
loggedIn()
else:
print("\nUsername or Password invalid\n")
def quit():
print("Goodbye! The program will now exit")
os.remove('./users/login.txt')
f = open('./users/login.txt', 'w')
for ele in users:
f.write(ele+'\n')
f.close()
sleep(2)
clear()
exit()
#end of login system
def loginsys():
folder_check = os.path.isdir('./users')
if (folder_check == True):
file_check = os.path.isfile('./users/login.txt')
if (file_check == True):
f = open('./users/login.txt', 'r+')
f1 = f.readlines()
for ele in f1:
users.append(ele)
f.close()
print(users)
loggedOut()
else:
f = open('./users/login.txt', 'w')
f.write('')
f.close()
loggedOut()
else:
os.mkdir('./users')
loginsys()
def menu():
print("Hello World")
loginsys()

readlines() puts a newline at the end of every text line. You can use rstrip() to remove it:
f = open('./users/login.txt', 'r+')
f1 = f.readlines()
for ele in f1:
users.append(ele.rstrip())

Append key and value to json file

I am making a user system. I need to store the usernames and passwords in a file.
Case 1: If existing user=
I need to read the username and password to check existing user.
I need to check if the passwords match from the keyed in value and from the dictionary value.
Case 2 : If new user=
I need to check if the username already exist in the database.
If not then, i need to append the username and password in existing file without overwriting.
The problem here, i have utilised json here but it seems to overwrite the existing dict.
I have tried writing to a simple text file and i encounter problem in case when reading the file and also when i check if username exists in case 2.
# Login System Management
import json
class LoginSystem:
def __init__(self): # Opening and reading the registered users json.file
self.users = json.load(open("Users.json"))
self.login_screen()
def login_screen(self): # Log on screen to verify new or old user.
while True:
main_log = input("Are you new user?\n[Y]es or [N]o: ")
if main_log == "Y":
self.new_user()
break
elif main_log == "N":
self.old_user()
break
else:
print("Invalid answer.\n")
def old_user(self): # Log in screen if old user.
while True:
user_id = input("Please enter your user id: ")
user_password = input("Please enter your password: ")
if len(user_id) <= 64 and len(user_password) <= 64 and self.check_system(user_id, user_password):
print("Logging In")
break
else:
print("Wrong password or username!\n")
def check_system(self, name, password): # Checking system to verify old user id and password.
data = self.users
try:
expected_password = data[name]
except KeyError:
return False
if password != expected_password:
return False
return True
def new_user(self): # Log in screen if new user.
while True:
print("\nMax Length is 64 chars.")
reg_id = input("Register your username: ")
reg_password = input("Key in password: ")
if len(reg_id) <= 64 and len(reg_password) <= 64:
if reg_id not in self.users:
print("Loading.....")
self.update_database(reg_id, reg_password)
print("Registered Successfully.")
break
else:
print("User already registered!\n")
self.old_user()
break
else:
print("Error. Max Length is 64 chars.\n")
def update_database(self, new_user_name, new_user_password): # Writing new username and password to json.file
new_username = new_user_name
new_password = new_user_password
field = [new_username, new_password]
with open("Users.json", "w") as f:
json.dump(field, f)
check = LoginSystem()

The problem is that you are opening the csv file in "write" mode. This mode replaces what you have written in the database so far with the new line. Use "append" instead.
with open("Users.json", "a") as f:

I had figure out the answer. If anyone wants to refer you can follow.
First, I have created a csv file with row of line username,password and save it in the same directory.
The rest as follows the code.
# Login System Management import csv import time
class LoginSystem:
def __init__(self): # Opening
self.login_screen()
def login_screen(self): # Log on screen to verify new or old user.
while True:
main_log = input("Are you new user?\n[Y]es or [N]o: ")
if main_log == "Y":
self.new_user()
break
elif main_log == "N":
self.old_user()
break
else:
print("Invalid answer.\n")
def old_user(self): # Log in screen if old user.
while True:
user_id = input("\nPlease enter your user id: ")
user_password = input("Please enter your password: ")
if len(user_id) <= 64 and len(user_password) <= 64 and self.read_database(user_id, user_password):
print("Successful")
break
else:
print("Wrong password or username!\n")
def new_user(self): # Log in screen if new user.
print("\nMax Length is 64 chars.")
reg_id = input("Register your username: ")
if self.check_database(reg_id) is True:
while True:
reg_password = input("Key in password: ")
if len(reg_id) <= 64 and len(reg_password) <= 64:
print("Loading.....")
time.sleep(2)
self.update_database(reg_id, reg_password)
print("Registered Successfully.")
break
else:
print("Error. Max Length is 64 chars.\n")
else:
print("User Already Exists.\n")
self.old_user()
def read_database(self, name, password): # Checking if password match to username
with open("Users.csv", "r") as f:
reader = csv.reader(f)
user_list = {}
for row in reader:
user_list[row[0]] = row[1]
try:
expected_password = user_list[name]
if password == expected_password:
print("Logging In")
time.sleep(2)
return True
except KeyError:
return False
if password != expected_password:
return False
def check_database(self, new_name): # Checking if new id exists in user database
with open("Users.csv", "r") as f:
reader = csv.reader(f)
user_list = {}
for row in reader:
user_list[row[0]] = row[1]
if new_name in user_list.keys():
return False
elif new_name not in user_list.keys():
return True
def update_database(self, new_user_name, new_user_password): # Writing new username and password to file
with open("Users.csv", "a", newline="\n") as f: # appends the new username and password to new row of line
writer = csv.writer(f)
writer.writerow([new_user_name, new_user_password])
check = LoginSystem()

Python - how to read through text file for keyword

**This is a practice application
I have a text file containing a id & a password. Each pair is on separate lines like so:
P1 dogs
P2 tree
I then have 2 functions to allow the user the add another id/password or update the password by selecting an ID then the new password. (I have removed the save functionality so I don't create loads of pairs when testing)
The question is how would I write a check function so that when the user is creating a new pair.. it checks if the id/password already exists. Then on the update password function, it only checks if the password exists?
My code so far:
#Keyword check
def used_before_check(keyword, fname):
for line in open(fname, 'r'):
login_info = line.split()
username_found = False
for line in login_info:
if keyword in line:
username_found == True
if username_found == True:
return True
else:
return False
# New password function
def new_password():
print("\nCreate a new password")
new_id_input = input("Please give your new password an ID: ")
new_password_input = input("Please enter your new password: ")
print("ID in use?", used_before_check(new_id_input, txt_file))
print("Password in use?", used_before_check(new_password_input, txt_file))
#Change password function
def change_password():
print("\nChange password")
id_input = input("Enter the ID of the password you'd like to change: ")
password_input = input("Now enter the new password: ")
print("password_input",used_before_check(password_input, txt_file))

The easiest way would be to use JSON:
import json
import os
def new_password(user, password, password_dict={}):
if user in password_dict:
password_dict[user] = password # change password
else:
password_dict[user] = password # new password
return password_dict
def read_passwords(filename):
if not os._exists(filename):
return {}
with open(filename, 'r') as f:
s = f.read()
return json.loads(s)
password_filename = 'my_passwords.json'
password_dict = read_passwords(password_filename)
user = ''
while not user == 'q':
user = input('user:')
password = input('new password:')
if user != 'q':
password_dict = new_password(user, password, password_dict)
s = json.dumps(password_dict)
with open(password_filename, 'w') as f:
f.write(s)
Not that I have included a seemingly unnecessary if clause in new_password. This is just for you that you can easily enter your own code what you want to do (maybe different) in each case.

Create a function to store your usernames/passwords in a dictionary, then you can easily check it for existing usernames/passwords
To store in dictionary:
def process_file(fname):
username_pw_dict = {}
for line in open(fname, 'r'):
login_info = line.rstrip().split()
username = login_info[0]
pw = login_info[1]
username_pw_dict[username] = pw
return username_pw_dict
username_pw_dict = process_file(fname)
Then you can check for existing usernames or passwords like this:
if new_username in username_pw_dict:
print("username already exists")
if new_pw in username_pw_dict.values():
print("password already exists")

When you are reading the file, make a dictionary with all the IDs as its keys.
In next step, reverse the dictionary key-value pair so all its values (i.e all passwords) become its keys.
Finally, when you enter a new ID and password, just check those dictionaries to know if they already exist. You may refer to this below code:
dict_ids = {1 : "one", 2:"two", 3:"three"};
dict_pwds = {}
for key, value in dict_ids.items():
for string in value:
dict_pwds[value] = key;
print "dict_ids ", dict_ids;
print "dict_pwds ", dict_pwds;
if 'myid' in dict_ids.keys():
print "ID exist! "
else:
print "New ID"
if 'mypwd' in dict_pwds.keys():
print "Password exist! "
else:
print "New Password"

csv - Creating a login system, python not properly reading from .csv file?

I am trying to make a login system that is looped basically and whenever I try to enter the correct details that are even stored in the .csv file, it outputs as incorrect username/password no matter what I put. This code works for python 3.6 but I need it to work for python 3.2.3.
loop1 = False #for this bit of code (logging in)
loop2 = False #for next bit of code
while loop1 == False:
choice = input("Login/SignUp [TYPE 'L' OR 'S']: ").lower()
if choice == "l":
username = input("Username: ")
password = input("Password: ")
f = open("usernamepassword.csv","r")
for line in f:
details = line.split(",")
if username == details[0] and password == details[1]:
print("Welcome")
break
#this whole bit of code is meant to read from the csv and check if the login details are correct
else:
print("Username/Password [INCORRECT]")

Allow me to refactor your code:
def login(username, password):
with open("usernamepassword.csv", "r") as csv:
all_details =
[[attr.strip() for attr in line.split(",")]
for line in csv]
return any(
username == details[0]
and password == details[1]
for details in all_details)
def login_action():
username = input("Username: ")
password = input("Password: ")
if not login(username, password):
raise ValueError("Username/Password [INCORRECT]")
return True
_USER_ACTIONS = {
'l': login_action
}
def main():
while True:
choice = input("Login/SignUp [TYPE 'L' or 'S']: ").lower()
action = _USER_ACTIONS[choice]
try:
if action():
break
except Exception as err:
print(err.message)
I think your unexpected behavior comes from not stripping the values you get after splitting by ,

Solved by replacing:
if username == details[0] and password == details[1]:
With:
if username == details[0] and (password+"\n") == details[1]:

You may have a bug in line.split(','), try line.strip().split(',')
TL; DR: posted a proper solution there : https://github.com/cgte/stackoverflow-issues/tree/master/47207293-csv-dict
I'll stuff up my answer later if needed.
Furthermore you have a poor code design here, and find yourself debugging in the middle of a loop.
So first of all : load the data file, store content to a dict.
f = open("usernamepassword.csv","r")
for line in f:
details = line.split(",")
if username == details[0] and password == details[1]:
print("Welcome")
break
Should become
user_pass = {}
f = open("usernamepassword.csv","r")
for line in f:
user, password = line.strip().split(",")
user_pass[user] = password
f.close()
or better
with open("usernamepassword.csv","r") as f:
for line in f.readlines():
user, password = line.split().split(",")
user_pass[user] = password
eventually run python -i yourfile.py and type "user_pass" to see what is actually stored when correct go on further code.
Think of using the csv module : https://docs.python.org/3/library/csv.html
Then get username and password from input and check:
if login in user_pass and user_pass[login] = password:
# or better `if user_pass.get(login, None) == password:`
do_stuff()

Dictionary empties after running program

I'm using python 2.7.5 and i'm trying to make a simple program that has a username, password, and checks if it exists in a dictionary. If true, it prints welcome + username, and ignores if false.
First: code.
#!/usr/bin/python
import csv
users = {}
with open('C:\\Users\\chef\\Python\\fn.csv', 'wb') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)
def new_user():
uname = raw_input("Choose a username: ")
while 1:
pwd = raw_input("Choose a password: ")
check = raw_input("Retype password: ")
if pwd == check:
print "Saved."
users[uname] = pwd
break
if uname in users.keys():
pass
def show_users():
for unames in users.keys():
print unames
def login():
uname = raw_input("Username: ")
pwd = raw_input("Password: ")
if uname in users and pwd in users.values():
print "Welcome, " + uname + "! "
def save():
f=open('C:\\Users\\chef\\Python\\fn.csv', "wb")
w = csv.writer(f)
for key, val in users.items():
w.writerow([key, val])
f.close()
def read():
with open('C:\\Users\\chef\\Python\\fn.csv', 'wb') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)
print "Welcome to Yubin's 'fake' Email server."
while 1:
read()
choice = raw_input("What would you like to do? ")
if choice == "signup":
new_user()
if choice == "login":
login()
if choice == "showusers":
show_users()
if choice == "logout":
print "You have successfully logged out."
if choice == "quit":
x = raw_input("Are you sure? (y/n) ")
if x == "y":
save()
break
else:
pass
else:
print "Please sign up, log in or see who have signed up."
Problems:
When I first "sign up", i can log in perfectly fine. But, after closing the program and running it again, i can't log in. i assume it's because i set the dictionary empty every time i start, but it's supposed to rewrite the contents into the dictionary. i use windows 7 and in the preview, when i rerun the program, the file becomes empty.
After i write either login, signup or showusers, it prints the last line,
"Please sign up, log in or see who have signed up. "
Please i ask for solutions, and thank you in advance.
EDIT: I solved problem #2, but #1 still is there.

The problem is, as hyades stated, that your read-method overwrites the csv-file instead of reading it. The csv-module offers a reader for this purpose. I have changed your read-method like this to make it work:
def read():
with open('C:\\Users\\chef\\Python\\fn.csv', 'r') as f:
usersReader = csv.reader(f)
for row in usersReader:
if row == []:
pass
else:
users[row[0]] = row[1]
f.close();
You can also remove the "with open..."-code block at the begining of the file (after import and users-declaration).

For Problem 1, might be an issue with the mode of the file. Change it to wb+
Opens a file for both writing and reading in binary format. Overwrites
the existing file if the file exists. If the file does not exist,
creates a new file for reading and writing.
Problem 2 will be solved if you use if..elif instead of if

Check this code above. I use only save and read function. I used read function only once, outside while loop (used 'rb' mode istaed 'wb' mode). I used csv.WriteDict and csv.ReadDict classes enter link description here. to read and save data from users dict. I think You can use shelve or json instead csv, propobly these way will by faster and simply ;)
#!/usr/bin/python
import csv
users = {}
'''def write():
with open('/home/marcin/fn.csv', 'wb+') as f: # Just use 'w' mode in 3.x
w = csv.DictWriter(f, users.keys())
w.writeheader()
w.writerow(users)'''
def new_user():
uname = raw_input("Choose a username: ")
while 1:
pwd = raw_input("Choose a password: ")
check = raw_input("Retype password: ")
if pwd == check:
print "Saved."
users[uname] = pwd
break
if uname in users.keys():
pass
def show_users():
for unames in users.keys():
print unames
def login():
uname = raw_input("Username: ")
pwd = raw_input("Password: ")
if uname in users and pwd in users.values():
print "Welcome, " + uname + "! "
def save():
with open('/home/marcin/fn.csv', "wb+") as f:
fieldnames=['user','pwd']
writer = csv.DictWriter(f,fieldnames=fieldnames)
writer.writeheader()
for key, val in users.items():
writer.writerow({'user' : key, 'pwd' : val})
def read():
with open('/home/marcin/fn.csv','rb') as f: # Just use 'w' mode in 3.x
w = csv.DictReader(f)
for row in w:
print row
users[row['user']]=row['pwd']
def main():
print "Welcome to Yubin's 'fake' Email server."
try:
read()
except IOError:
pass
while 1:
choice = raw_input("What would you like to do? ")
if choice == "signup":
new_user()
save()
if choice == "login":
login()
if choice == "showusers":
show_users()
if choice == "logout":
print "You have successfully logged out."
if choice == "quit":
x = raw_input("Are you sure? (y/n) ")
if x == "y":
save()
break
else:
pass
else:
print "Please sign up, log in or see who have signed up."
if __name__ == "__main__":
main()