I am new to Python and am having trouble with looping while checking strings in a file. For this program, I am checking to see if a username that the user wants to create already exists. If the username already exists in the file, the program prompts the user to enter another username. The loop ends when the user enters a username that is not in the file. Here is the relevant code:
# Prompting for username and password
username = input("Enter your username: ")
password = input("Enter your password: ")
# open password file
f = open("password.txt", "r")
# while username exists in file
while username in f.read():
username = input("Enter your username: ")
f.close()
If I enter a username that exists in the password file, the program does prompt me to enter another username; however, when I enter the same username, the program does not stay in the loop. Any ideas on why this is occurring?
When you run f.read() Python will read the file in and then continue onto the next line of the file in the next iteration. It wont go back to the top of the file. So it exits the loop since the username in the next line of the file is either an empty string or another name. To fix this you could use a context manager like so:
# Prompting for username and password
username = input("Enter your username: ")
password = input("Enter your password: ")
# read in the file data
with open('password.txt') as f:
data = f.read()
# while username exists in file
while username in data:
username = input("Enter your username: ")
Then depending on how the data is structured in your .txt file then you can call split() on data if it's using a new line.
There is no condition to check whether the new username is in the file or not.
Maybe an easier way to do this would be to use the following approach?
username = input("Enter your username: ")
password = input("Enter your password: ")
# open password file
f = open("password.txt", "r")
data = f.read()
# while username exists in file
while username in data:
new = input("Enter your username: ")
if new in data:
continue
else:
break
username = new
f.close()
This is because you are using f.read() in the while condition.
f.read reads the whole content of the file at once and there's nothing else to read from file, leading to the end of while loop.
If you want to check for usernames in the file, I'd suggest you create a list of usernames that you read from the file and use it in your while loop for checking.
If your file has contents:
username1, username2, ...
You can do
listOfUsernames = f.read().split(',')
and then use this for checking in while loop.
Related
I am making a small simple password manager in python. I have the functions of creating an account which has 3 inputs, Username, Password, and Website. I have a function to view all the accounts which shows the contents of the file info.txt where all that information goes. Im trying to create a function to delete an entry but im not sure how to make the function delete all the lines of information associated with the Username. I want an input asking "Which account to delete" you put the username, and it will delete all information associated with the username in info.txt
Code:
import os.path #Imports os module using path for file access
def checkExistence(): #Checking for existence of file
if os.path.exists("info.txt"):
pass #pass is used as a placeholder bc if no code is ran in an if statement and error comes.
else:
file = open("info.txt", "w") #creates file with name of info.txt and W for write access
file.close()
def appendNew():
#This function will append a new password in the txt file
file = open("info.txt", "a") #Open info.txt use a for appending IMPORTANT: opening a file with w for write will write over all existing data
userName = input("Enter username: ")
print(userName)
os.system('cls')
password = input("Enter password: ")
print(password)
os.system('cls')
website = input("Enter website: ")
print(website)
os.system('cls')
print()
print()
usrnm = "Username: " + userName + "\n" #Makes the variable usrnm have a value of "Username: {our username}" and a new line
pwd = "Password: " + password + "\n"
web = "Website: " + website + "\n"
file.write("----------------------------------\n")
file.write(usrnm)
file.write(pwd)
file.write(web)
file.write("----------------------------------\n")
file.write("\n")
file.close()
def readPasswords():
file = open("info.txt", "r") #Open info.txt with r for read
content = file.read() # Content is everything read from file variable (info.txt)
file.close()
print(content)
checkExistence()
while True:
choice = input("Do you want to: \n 1. Add account\n 2. View accounts\n 3. Delete account\n")
print(choice)
if choice == "1":
os.system('cls')
appendNew()
elif choice == "2":
os.system('cls')
readPasswords()
elif choice == "3":
os.system('cls')
else:
os.system('cls')
print("huh? thats not an input.. Try again.\n")
I tried making a delete account function by deleting the line which matched the username. My only problem is that it only deletes the line in info.txt with the username, but not the password and website associated with that username.
Firstly, you're using the wrong tool for the problem. A good library to try is pandas, using .csv files (which one can think of as pore program oriented excel files). However, if you really want to use the text file based approach, your solution would look something like this:
with open(textfile, 'r+') as f:
lines = [line.replace('\n', '') for line in f.readlines()]
# The above makes a list of all lines in the file without \n char
index = lines.index(username)
# Find index of username in these lines
for i in range(5):
lines.pop(index)
# Delete the next five lines - check your 'appendNew' function
# you're using five lines to write each user's data
print(lines)
f.write("\n".join(lines))
# Finally, write the lines back with the '\n' char we removed in line 2
# Here is your readymade function:
def removeName(username):
with open("info.txt", 'r+') as f:
lines = [line.replace('\n', '') for line in f.readlines()]
try:
index = lines.index(username)
except ValueError:
print("Username not in file!")
return
for i in range(5):
lines.pop(index)
print(lines)
f.write("\n".join(lines))
# Function that also asks for username by itself
def removeName_2():
username = input("Enter username to remove:\t")
with open("info.txt", 'r+') as f:
lines = [line.replace('\n', '') for line in f.readlines()]
try:
index = lines.index(username)
except ValueError:
print("Username not in file!")
return
for i in range(5):
lines.pop(index)
print(lines)
f.write("\n".join(lines))
# Usage:
removeName(some_username_variable)
removeName_2()
Again, this is a rather clunky and error prone approach. If you ever change the format in which each user's details are stored, your would have to change the number of lines deleted in the for loop. Try pandas and csv files, they save a lot of time.
If you're uncomfortable with those or you're just starting to code, try the json library and .json files - at a high level they're simple ways of storing data into files and they can be parsed with the json library in a single line of code. You should be able to find plenty of advice online about pandas and json.
If you're unable to follow what the function does, try reading up on try-except blocks and function parameters (as well as maybe global variables).
I have been trying to work out how to look for matching words in a csv file, such a user account detail.
What I have already done is creating two csv files with a username in one and a password in the other, putting them into python and then create a script that lets the user log in, but I can't get it to search for just one username if there are more than one in the csv file.
Here is my code:
import csv
#imports and loads usernames and passwords
usernames = []
passwords = []
infile = open("usernames.csv",'r')
reader=csv.reader(infile)
for i in reader:
usernames.append(i)
infile.close()
infile = open("passwords.csv",'r')
reader=csv.reader(infile)
for i in reader:
passwords.append(i)
infile.close()
#the log in script
def login():
print("Please enter your username:")
userlogin=input()
print("Please enter your password:")
passlogin=input()
if userlogin in usernames and passlogin in passwords:
print("Welcome, " + userlogin)
else:
print("Sorry, that's not a valid login")
Thank you for any help given
I think there is a flaw in your approach.
You cannot combine any username with any password.
If you are going to use your code this way,
One password will become applicable for all.
Try to create a dictionary or some kind of mapping where a single password will be checked instead of all present passwords.
If you want to add them, I would suggest using a pandas dataframe which will give you structure and checking will be easier as well.
import pandas as pd
df = pd.DataFrame()
df['usernames'] = pd.read_csv('usernames.csv')
df['passwords'] = pd.read_csv('passwords.csv')
if df[(df['usernames'] == your_user_name) &
(df['passwords'] == your_password)].empty() is not True:
print("username and password present")
else:
print("username and password not present")
I have a code where I have an email and a password in a text file in a list, formatted like this: ["tom#gmail.com","Password1"],["harry#gmail.com","Password2].
My code reads from the text file and compares it with a user input to see if it is present in the text file. For some reason when I input the first email "tom#gmail.com" it reads that from the text file but not "Password1", however it reads "harry#gmail.com" correctly as well as "Password2" correctly. I cant find any way to get around this and fix this? No error is received so I'm not sure where its going wrong. Here is my code:
def Login():
with open("logindata.txt","r") as file:
for line in file:
line=line.split(",")
logindata.append([line[0],line[1].rstrip()])
print(logindata)
found=False
while found == False:
email=input("Enter email:")
password=input("Enter password:")
with open("logindata.txt","r")as file:
for line in file:
line = line.split(",")
if email in line:
print("Correct email")
if password in line:
print("Correct Password")
found=True
if __name__ == "__main__":
Login()
if the code is run and you try the inputs I gave at the start then only the second email and password combination works. Here is what the text file looks like text file format
Appending:
username=input("Enter a new email")
password=input("Enter a password")
with open('logindata.txt','a')as file:
line='\n'+ username + ',' + password
file.write(line)
print("user added")
You are reading text with line separators. Your lines don't look like this:
tom#gmail.com,Password1
They actually look like this:
tom#gmail.com,Password1\n
When splitting that on the comma, you get this:
line = ['tom#gmail.com', 'Password1\n']
and the test 'Password1' in line fails, but 'Password1\n' in line would succeed.
The \n is a newline character. You'd need to remove that first; you could use str.strip() to handily remove all whitespace from the start and end:
for line in file:
line = line.strip().split(",")
if email in line:
print("Correct email")
if password in line:
print("Correct Password")
Rather than manually split, you can use the csv module to read your file:
import csv
with open("logindata.txt", "r") as file:
reader = csv.reader(file)
for user, pw in reader:
if email == user:
print("Correct email")
if password == pw:
print("Correct Password")
I am producing a turn based game for a project and would like to create a user login system that saves the user's login username and password into a file in the game folder location. I would hope to then use the notepad file to check if there is already an account with that username when new users try to create a login.
In this code i attempted this but it is wrong?!
filename = 'UserInfo.txt'
openfile = open(filename, "r")
UserData = openfile.readline()
def displayMenu():
print (UserData)
status = input("Are you a registered user? y/n? ")
if status == "y":
oldUser()
elif status == "n":
newUser()
def newUser():
createLogin = input("Create login name: ")
if createLogin in UserData:
print ("Login name already exist!")
else:
createPassw = input("Create password: ")
UserData[createLogin] = open('UserInfo','w')
print("User created!")
def oldUser():
login = input("Enter login name: ")
passw = input("Enter password: ")
if login in UserData and UserData[login] == passw:
print ("Login successful!")
else:
print ("User doesn't exist or wrong password")
displayMenu()
You should really be putting the error message up but I think I have spotted what is wrong. In newUser() you are opening 'UserInfo' not 'UserInfo.txt' also open in a mode not w mode. So write open('UserInfo.txt', 'a')
You also need to read all the lines not just one line openfile.readlines()
Also remember to close the file after you open it in read mode or else it wont let you write to it:
openfile = open(filename, "r")
UserData = openfile.readline()
openfile.close();
For the file you need to read all lines instead of line so use openfile.readlines() to check if login in UserData. And whenever you create a new user you need to append the new user into your file instead of overwriting the existing data in your file. So instead of using open('UserInfo.txt', 'w') you need to open with a mode like open('UserInfo.txt', 'a') which will append new data to the end of the file.
I'm a beginner in Python and ran across an error. I am trying to create a programme that will take a username and password made by a user, write them into lists and write those lists to files. Here is some of my code:
This is the part where the user is creating a username&password.
userName=input('Please enter a username')
password=input('Please enter a password')
password2=input('Please re-enter your password')
if password==password2:
print('Your passwords match.')
while password!=password2:
password2=input('Sorry. Your passwords did not match. Please try again')
if password==password2:
print('Your passwords match')
My code works fine up until this point, where I get the error:
invalid file: <_io.TextIOWrapper name='usernameList.txt' mode='wt' encoding='cp1252'>.
I'm not sure why this error is being returned.
if password==password2:
usernames=[]
usernameFile=open('usernameList.txt', 'wt')
with open(usernameFile, 'wb') as f:
pickle.dump(usernames,f)
userNames.append(userName)
usernameFile.close()
passwords=[]
passwordFile=open('passwordList.txt', 'wt')
with open(passwordFile, 'wb') as f:
pickle.dump(passwords,f)
passwords.append(password)
passwordFile.close()
Is there any way to fix the error, or another way to write the lists to a file?
Thanks
You had the right idea, but there were a number of issues. When the user passwords do not match, normally you would prompt for both again.
The with block is designed to open and close your files, so there is no need to add a close at the end.
The script below shows what I mean, you will then have two files holding a Python list. So trying to view it will not make much sense, you will now need to write the corresponding read part to your code.
import pickle
userName = input('Please enter a username: ')
while True:
password1 = input('Please enter a password: ')
password2 = input('Please re-enter your password: ')
if password1 == password2:
print('Your passwords match.')
break
else:
print('Sorry. Your passwords did not match. Please try again')
user_names = []
user_names.append(userName)
with open('usernameList.txt', 'wb') as f_username:
pickle.dump(user_names, f_username)
passwords = []
passwords.append(password1)
with open('passwordList.txt', 'wb') as f_password:
pickle.dump(passwords, f_password)
usernameFile=open('usernameList.txt', 'wt')
with open(usernameFile, 'wb') as f:
In the second line usernameFile is a file object. The first argument to open must be a file name (io.open() also supports file descriptor numbers as ints). open() tries to coerce its argument to a string.
In your case, this results in
str(usernameFile) == '<_io.TextIOWrapper name='usernameList.txt' mode='wt' encoding='cp1252'>'
which is not a valid filename.
Replace with
with open('usernameList.txt', 'wt') as f:
and get rid of usernameFile completely.