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how can i make store a username in txt file without having the same username twice?

user = input("\nInput user's Login ID: ")
while True:
password = str(input ("Input user's Password: "))
rpass = str(input("Re-enter the Password: "))
if password == rpass:
file = open("username.txt", "a")
file.write (user)
file.close()
break
else:
print("You have entered the wrong password, Try Again")
I want make a program where users can sign up with their username and password and it can be stored into a txt file. And the next person that is going to sign up won't be able to use the same username.
I renewed the code but the same problem happened, the previous username is not detected.

Every time you write to the file, it appends to the same line.
if data == user+ ":" +password:
This condition is never true as a result.
One possible solution is to add \n after every write.
file.write (user +" : "+ password +"\n")
And your condition would be
if data == user+ " : " +password:
Be mindful of whitespaces and other characters. It should be an exact match with this method.
Edit: You're checking whether the new username and password together are a match.
What you should be doing is matching user with data.split(':')[0][:-1] -
if data.split(":")[0][:-1] == user
This will collect the string till the ':' and truncate the trailing space.

If you want to use the parse module, you can run pip install parse and use this code:
import parse
pattern = '{[a-z][A_Z][0-9]} : {[a-z][A_Z][0-9]}'
lines = []
user = input ("enter username: ")
password = input ("enter password: ")
with open('username.txt', 'r') as f:
line = f.readline()
while line:
u, p = parse.parse(pattern, line)
lines.append((u, p))
line = f.readline()
users = [ u for (u, p) in lines ]
if user in users:
print(f'Username {user} is taken, please try again.')
else:
with open('username.txt', 'a') as f:
f.write(f'{user} : {password}')
print(f'Username and password successfully created.')

Python - Read each line of text file and pass each line to variable

I am attempting to implement a simple password checker which will allow the user to open a text file that contains generated passwords and check them against a list of criteria to see if the password is strong or weak. It should then output the password with the result of whether it is strong or weak.
With the current solution I can get the list of passwords to print, but when the check as to whether the password is strong or not, only one result is shown. I am attempting for the output to be the password that is generated with the result e.g. Randompassword123 - This is a weak password.
Below is the code I am currently using:
def multiplestrength(): # password strength check function
textfile = filedialog.askopenfilename(initialdir="/home", title = "Select text file to split",filetypes = (("text files","*.txt"),("all files","*.*")))
with open(textfile , mode="r",encoding="utf-8") as my_file:
data=my_file.read()
print(data)
def strongPassword(data):
if passRegex1.search(data) == None:
return False
if passRegex2.search(data) == None:
return False
if passRegex3.search(data) == None:
return False
if passRegex4.search(data) == None:
return False
else:
return True
passRegex1 = re.compile(r'\w{8,}')
passRegex2 = re.compile(r'\d+')
passRegex3 = re.compile(r'[a-z]')
passRegex4 = re.compile(r'[A-Z]')
if strongPassword(data) == True:
print("Strong Password")
else:
print("This is not a strong password")
The output I receive is below
So it appears that only one password is being checked from the list of 5 passwords in the text file. I believe there might need to be a for loop required somewhere for each password to be checked, but I am unsure what way to approach this. Another approach I was thinking would be to insert the passwords from the text file into a list and iterating through this list to get a result for each password. Does this possibly sound like the correct way to approach this?
Any help with this would be greatly appreciated.
Thanks

I have written a solution. I have added many comment for code as description.
Code:
import re
passRegex1 = re.compile(r'\w{8,}')
passRegex2 = re.compile(r'\d+')
passRegex3 = re.compile(r'[a-z]')
passRegex4 = re.compile(r'[A-Z]')
def strong_password(data): # the function name should be snake case
if not passRegex1.search(data): # Use "if not". It is the Pythonic way. It handles False/None/0/""/[] etc...
return False
if not passRegex2.search(data):
return False
if not passRegex3.search(data):
return False
if not passRegex4.search(data):
return False
else:
return True
with open("test.txt", mode="r", encoding="utf-8") as my_file: # Open file for reading
for line in my_file.readlines(): # Read all lines one-by-one
print("\nPassword: {}".format(line.strip())) # Print the current password ("strip" removes the whitespace characters from string).
if strong_password(line): # This statement is True if the "strong_password" function returns True
print("Strong Password")
continue # Get the next element (line of file)
print("This is not a strong password") # Else statement is not needed because the "if" contains a continue
My test file:
asdf
121234
adsf123
asdffdsatre323423
fdggfd2323____,,,**
tt
333345
asdfSDFGRAdsfAERTGRghRGads___++((((FDsaSDfAS4233423524
434
55555
Output:
>>> python3 test.py
Password: asdf
This is not a strong password
Password: 121234
This is not a strong password
Password: adsf123
This is not a strong password
Password: asdffdsatre323423
This is not a strong password
Password: fdggfd2323____,,,**
This is not a strong password
Password: tt
This is not a strong password
Password: 333345
This is not a strong password
Password: asdfSDFGRAdsfAERTGRghRGads___++((((FDsaSDfAS4233423524
Strong Password
Password: 434
This is not a strong password
Password: 55555
This is not a strong password

You could loop through the lines of your file using:
with open(textfile , mode="r",encoding="utf-8") as my_file:
for line in my_file:
# do something with the line, eg:
if strongPassword(line):
# ...
Edit: you might want to use line.strip() instead of line to get rid of the newline characters at the end (\n)

Python: how do I compare two lists (username & password) read from a .txt to a user input

I have written a code that is supposed to request a user to input a username and password. The program should then open a .txt file containing a list of usernames and passwords and check to see if the entered entries are valid against username and password database in the .txt file. This is the first time I am posting here so please advise what else you would require. I have hopefully attached my .py file and .txt file.
I am able to input the first username and password, but the second one, I have to input twice in order for it to be successful. I'm sure that is due to the for loop, but then I do not know how else to do the compare the inputs with the username and passwords stored in the .txt
#======== User Login ====================
#read the use.txt
username_reg = []
password_reg = []
i = 0
username_list = []
password_list = []
with open('user.txt', 'r+') as f: #open user.txt
for line in f: #Now we reading user.txt
line = line.replace(" ", "") #replace space before password with no space
line = line.replace("\n", "") #remove the next line character as this will take a space in the list
line = line.split(",") #separate user name and password
username_reg = line[0]
password_reg = line[1]
username_list.append(username_reg)
password_list.append(password_reg)
#List check
print(username_list)
print(password_list)
print(len(username_list))
username = input("Please enter username: ")
password = input("Please enter password: ")
for i in range(len(username_list)):
if username == str(username_list[i]) and password == str(password_list[i]):
print('''Please select one of the following options:
r - register user
a - add task
va - view all tasks
vm - view my tasks
e - exit''')
break
while username != str(username_list[i]) and password != str(password_list[i]):
print("invalid username or password")
username = input("Please enter username: ")
password = input("Please enter password: ")
i += 1
print("Great success")

I would approach this in a different way. Dictionaries work great when it comes to associate some specific data to a entity. In this case, I would use one to associate the password to each username.
Considering that your database stores the info as follows:
user1, password1
user2, password2
user3, password3
Then we can perform the following operation:
content = {}
with open('db.txt', 'r') as file:
for line in file.read().splitlines():
user = line.split(', ')
content.update({user[0]: user[1]})
username = input("Please enter username: ")
password = input("Please enter password: ")
if password == content[username]:
print('''Please select one of the following options:
r - register user
a - add task
va - view all tasks
vm - view my tasks
e - exit''')
We are basically opening the file, reading its lines (by using the splitlines() function of the str class), and the iterating over each line, separating the username and the password (by using split(', ') because ', ' is the separator) and updating the contentdictionary with a new record corresponding to each user.
Then, after asking for credentials, we just look the given username in our content dictionary and check that the password is the same.

I have tried to modify the for loop a bit and it works for me. Take a look.
i = 0; login = 0 #Here login is like a flag. Which get the value 1 once the login is successful else stays 0.
while i < len(username_list):
if username == str(username_list[i]) and password == str(password_list[i]):
login = 1
print('''Please select one of the following options:
r - register user
a - add task
va - view all tasks
vm - view my tasks
e - exit''')
break
i+=1
if i==len(username_list) and login == 0:
print("invalid username or password")
username = input("Please enter username: ")
password = input("Please enter password: ")
i = 0
The second if condition in the for loop checks if the login is not successful for all the values in the lists, it means the username and passwords are incorrect, so the if condition asks for the new inputs and resets the while loop to start again from 0.

Command only reads first line of text file

I have to make a program in which one of the functions is retrieval of usernames and results from a text file. (All on the same line)
For some reason, when I run it, only the first line is printed out. Why is this ? Also, this only happens when I try to run the program at school (part of an assignment), it prints everything it needs to on my laptop at home. (Python versions are also the same)
Here is my code :
def results():
username = input("Enter username :")
for line in open("resultsfile.txt","r"):
if username in line:
print (line)
elif username not in line:
("No such user")
Also, this is what the text file looks like (without bullet points) :
tud16 CS Easy 2points
ser23 CH Med 4points
tud16 CS Hard 1points

def results():
username = input("Enter username :")
for line in open("resultsfile.txt","r"):
if username in line:
print (line)
else:
print("No such user")
results()

You are iterating over a file but you are printing No such user for every line that does not match the username.
What you should do is evaluate after the loop if one of the lines in the file contained the username. To implement this you could introduce a boolean (found) indicating if a user has been found or not:
def results():
found = False
username = input("Enter username :")
for line in open("resultsfile.txt","r"):
if username in line:
print (line)
found = True
if not found:
print("No such user")

Python read next line from what the user inputs

So basically I have a program which can create a users username and password in a document and search for the password used with the username that is input by the person using the program.
For example:
The programs asks me to input a username I enter: '13'.
Under 13 in the text document is 'sadfsdfsdf'.
I want the program to skip to below the 'Username: 13' and read and print 'Password: sadfsdfsdf'.
note that I have multiple usernames and passwords In the .txt file
u = 'Username: '
Thanks in advance!
def SearchRecordProgram():
while True:
user_search = input("Please enter the username you wish to see the password for: ")
full_user = u + user_search
if full_user in open('User_Details.txt').read():
print(" ")
print ("Username found in our records")
print(" ")
print(full_user)
break
else:
print("Username entered does not match our records")

So, imagining your file is like so:
Username : 13
Password : sadfsdfsdf
Username : 15
Password : Lalalala
You can parse it (with regular expressions) like so:
import re # regular expression module
regex = re.compile("Username :(.*)\nPassword :(.*)")
# read text from file
with open(filePath,'r') as f:
text = f.read()
u_pass = regex.findall(text)
# [(' 13', ' sadfsdfsdf'), (' 15', ' Lalalala')]
user_dict = {u:password for u,password in u_pass}
# {' 13': ' sadfsdfsdf', ' 15': ' Lalalala'}
Now you can get the password of someone by asking for the password of that user :
# given username and password_input
if username in user_dict and user_dict[username] == password_input:
# if username exists and password okay
print "Authentication succeeded."

When you want to open a file, you should almost always use the with statement:
with open('User_Details.txt') as read_file:
# Do reading etc. with `read_file` variable
This will ensure that any errors are being handled correctly and the file is not left open.
Now that the file is open, we need to loop through each line until we find one that matches our username. I hope you know how for loop works:
username = 'Username: 13' # Get this however you want
with open('User_Details.txt') as read_file:
for line in read_file:
line = line.strip() # Removes any unnecessary whitespace characters
if line == username:
# We found the user! Next line is password
And we need to get the next line which contains the password. There are many ways to get the next line, but one simple way is to use the next() function which simply gets us the next element from an iterable (the next line from a file in this case):
username = 'Username: 13'
with open('User_Details.txt') as read_file:
for line in read_file:
line = line.strip()
if line == username:
password = next(read_file)
break # Ends the for loop, no need to go through more lines
Now you have a password and an username, and you can do whatever you want with them. It's often a good idea to have the inputs and outputs outside of your program's logic, so don't print the password right inside the for loop, but instead just receive it there and then do the printing outside.
You might even wanna turn the whole search logic into a function:
def find_next_line(file_handle, line):
"""Finds the next line from a file."""
for l in file_handle:
l = l.strip()
if l == line:
return next(file_handle)
def main():
username = input("Please enter the username you wish to see the password for: ")
username = 'Username: ' + username
with open('User_Details.txt') as read_file:
password = find_next_line(read_file, username)
password = password[len('Password: '):]
print("Password '{0}' found for username '{1}'".format(password, username))
if __name__ == '__main__':
main()
Finally, it's absolutely insane to store anything in this format (not to mention password security stuff, but I get you're just learning stuff), why not do something like:
username:password
markus:MarkusIsHappy123
BOB:BOB'S PASSWORD
This could then easily be converted into a dict:
with open('User_Details.txt') as read_file:
user_details = dict(line.strip().split(':') for line in read_file)
And now to get a password for an username, you'd do:
username = input('Username: ')
if username in user_details:
print('Password:', user_details[username])
else:
print('Unknown user')

Maybe not the pretties, but something like this will work:
with open(users_file, "r") as f:
lines = f.read()
def get_password(user_id):
entries = iter(lines.splitlines())
for entry in entries:
if(entry.startswith("{}:{}".format(prefix, user_id))):
return next(entries)
print "Password:", get_password("13")

def SearchRecordProgram():
while True:
user_search = input("Please enter the username > ")
file = open('User_Details.txt')
usernames = file.readlines() # Read file into list
file.close()
if user_search in usernames: # Username exists
print ('Found Username')
password = usernames[usernames.index(user_search)+1]
print ('Password is: ' + password)
break # Exit loop
else: # Username doesn't exist
print("Username entered does not match our records")
Note that this will not work if a password happens to be a username, e.g:
user1
password1
user2
user3 # This is the password for user3
user3
password3
If you search for "user3" this code will output "user3" as the password for "user3" because it finds the first instance of "user3" (line 4) and then looks to the next line (line 5), which is the next username.
Even worse, if "user3" is the last line in the file, it will end with an error because there are no more lines. You could add a check that the index of the found username is even (i.e. index 0, 2, 4, 8) with this code:
if not usernames.index(user_search) % 2: # Checks the remainder after / by 2.
# If it's 0 then it's an even index.
password = usernames[usernames.index(user_search)+1]
print ('Password is: ' + password)
but there isn't much you can do if this happens.
However, you could manipulate the file of usernames to only have usernames like this:
lst = [0, 1, 2, 3, 4, 5, 6, 7]
print (lst[0::2])
which prints
[0, 2, 4, 6]
So the code could be changed to this:
def SearchRecordProgram():
while True:
user_search = input("Please enter the username > ")
usernames = open('User_Details.txt').readlines() # Read file into list
if user_search in usernames[0::2]: # Username exists
print ('Found Username')
password = usernames[1::2][usernames[0::2]].index(user_search)]
print ('Password is: ' + password)
break # Exit loop
else: # Username doesn't exist
print("Username entered does not match our records")
Here is a breakdown
password = usernames[1::2] # Gets the odd items (passwords)
[ # Get index item. The index returned from searching
# the usernames will be the same as the index needed
# for the password, as looking at just the odd items:
# [0, 2, 4, 6]
# [1, 3, 5, 7] - even has the same index as next odd.
usernames[0::2] # Gets even items (usernames)
].index(user_search)]
# Only searches the usernames. This
# means passwords being the same is not
# an issue - it doesn't search them