Python - First project user system

Question

This code is supposed to be the "user" system for my app. This will ask you what you want to do...

If you want to add a user, remove a user or check the list of saved users. With this I learned how to open and edit text files. And my goal doing projects is keep on learning and maybe someday I will be able to work or professionally use Python.

This code is working at the moment, but I wanted to know if is too basic or too complicated with some more professional eyes on it (please consider my 3 weeks knowledge).

snames = list()
f_n = (open('names.txt')).read()
print("Welcome to NAME.app")
##################    USER   LOGG IN        #######################
while True:
    name = input("\n - Insert name to logg in \n - ADD to save new user \n - LIST to see saved users \n - REMOVE to delete a user \n - EXIT to finish \n ...")
    if name.lower() == "add":
        n_input = input("Name:")
        with open('names.txt', 'a') as f:
            f.write(n_input + '\n')
            f.close()
        continue

    elif name.lower() == "list":
        with open('names.txt') as f:
            print(f.read().splitlines())

    elif name in f_n:
        print("Logged as", name.upper())
        nxt = input('Welcome, press enter to continue \n')
        if nxt == '':
            break

    elif name.lower() == 'remove':
        rem = input("Insert user name to remove \n ...")
        with open('names.txt', 'r+') as f:
            l=f.readlines()
            l=[z for z in l if rem not in z]
        with open('names.txt', 'w') as f:
            f.writelines(l)


    elif name.lower() == "exit":
        exit()

Answer 1

Here is the review:

---

1. Always use with when opening a file, there are no exceptions. If you use .read(), when the user enters, for example, "Jan", while the names.txt file doesn't have has "Jan", but has "Jannet", the program will still return True for "Jan" in f_n. You can fix the problem using .splitlines() instead:

f_n = (open('names.txt')).read()

to

with open('names.txt', 'r') as r:
    f_n = r.read().splitlines()

---

2. You can drastically improve the readability of a multi-line string using triple-quotes.

menu = "\n - Insert name to logg in \n - ADD to save new user \n - LIST to see saved users \n - REMOVE to delete a user \n - EXIT to finish \n ..."

to

menu = """\
- Insert name to log in
- ADD to save new user
- LIST to see saved users
- REMOVE to delete a user
- EXIT to finish
... """

---

3. You do not need to assign an input statement to a variable in order for it to pause the program until the user presses ENTER.

nxt = input('Welcome, press enter to continue \n')
if nxt == '':
    break

to

input('Welcome, press enter to continue \n')

---

4. Since the continue isn't necessary, as none of the elif statements will execute if the program reaches that point anyway. Also, there is no need to use .close(), as the file handler does it for you:

    if name.lower() == "add":
        n_input = input("Name:")
        with open('names.txt', 'a') as f:
            f.write(n_input + '\n')
            f.close()
        continue

to

    if name.lower() == "add":
        n_input = input("Name:")
        with open('names.txt', 'a') as f:
            f.write(n_input + '\n')

---

5. You can increase the efficiency of your code by directly iteration through a given generator, instead of turning the generator into a list first. To detect whether two strings are equal or not, using the not in operator is prone to cause bugs. For example, 'Bob' not in 'Bobble' returns False, but they are different strings. Instead, use the != operator, as 'Bob' != 'Bobble' returns True:

    elif name.lower() == 'remove':
        rem = input("Insert user name to remove \n ...")
        with open('names.txt', 'r+') as f:
            l = f.readlines()
            l = [z for z in l if rem not in z]
        with open('names.txt', 'w') as f:
            f.writelines(l)

to

    elif name.lower() == 'remove':
        rem = input("Insert user name to remove \n ...")
        with open('names.txt', 'r+') as f:
            l = [z for z in f if z != rem]
        with open('names.txt', 'w') as f:
            f.writelines(l)

---

Altogether:

snames = list()
with open('names.txt', 'r') as r:
    f_n = r.read().splitlines()

print("Welcome to NAME.app")
menu = """\
- Insert name to logg in
- ADD to save new user
- LIST to see saved users
- REMOVE to delete a user
- EXIT to finish
... """

##################    USER   LOGG IN        #######################
while True:
    name = input(menu)
    if name.lower() == "add":
        n_input = input("Name:")
        with open('names.txt', 'a') as f:
            f.write(n_input + '\n')
    elif name.lower() == "list":
        with open('names.txt') as f:
            print(f.read().splitlines())
    elif name in f_n:
        print("Logged as", name.upper())
        input('Welcome, press enter to continue \n')
    elif name.lower() == 'remove':
        rem = input("Insert user name to remove \n ... ")
        with open('names.txt', 'r') as f:
            l = [z for z in f if z != rem]
        with open('names.txt', 'w') as f:
            f.writelines(l)
    elif name.lower() == "exit":
        exit()

```

Answer 2

First thing I notice is that this...

nxt = input('Welcome, press enter to continue \n')
if nxt == '':
    break

...could just be:

input('Welcome, press enter to continue')

It doesn't seem like you're using nxt for anything else so there's no need to store a value for it, especially if you just want the user to hit enter.

---

Next, you never do f_n.close() which can cause some issues with the file (e.g., it doesn't save or something weird happens with the garbage collector system, etc.).

You might want to replace...

elif name.lower() == "exit":
    exit()

...with:

elif name.lower() == "exit":
    f_n.close()
    exit()

The same should be done with the file in the first elif. Something I also noticed about this is that f_n is the same file as f. You shouldn't need to keep opening it; just use the f_n variable.

---

Instead of...

if name.lower() == "add":
    n_input = input("Name:")
    with open('names.txt', 'a') as f:
        f.write(n_input + '\n')
        f.close()
    continue

...with:

if name.lower() == "add":
    n_input = input("Name:")
    with open('names.txt', 'a') as f:
        f.write(n_input + '\n')
        f.close()

You don't need to say continue because the rest of the while loop is just elifs.

---

In terms of overall code style, mostly good, but there are a few things you might want to keep in mind:

1. Put spaces around equals signs for readability (e.g., use n = 10 instead of n=10).
2. It's spelled "log" not "logg."
3. I don't see a usage of snames, so is it really necessary?
4. The first comment in your code looks rather odd. Maybe just say # USER LOGIN , use a simple block comment, or, if you have to:

##############
# USER LOGIN #
##############

---

Hope this helps! If I think of something else, I'll edit it in.

Answer 3

Code after the opinions. Thank you very much for taking the time, I understand most of your points which makes me happy that I'm not too lost. Soon second part of my project another menu.

   with open('names.txt', 'r') as r :
    f_n = r.read().splitlines()
print("Welcome to NAME.app")
##############
# USER LOGIN #
##############
while True:
    name = input("""
    \n - Insert name to logg in
    \n - ADD to save new user
    \n - LIST to see saved users
    \n - REMOVE to delete a user
    \n - EXIT to finish
    \n - ...""")

    name = name.lower()

    if name == "add":
        n_input = input("Name:")
        with open('names.txt', 'a') as f:
            f.write(n_input + '\n')
            f.close()

    elif name == "list":
        with open('names.txt') as f:
            print(f.read().splitlines())
            f.close()

    elif name in f_n:
        print("Logged as", name.upper())
        input('Welcome, press enter to continue \n')
        break

    elif name == 'remove':
        rem = input("Insert user name to remove \n ...")
        with open('names.txt', 'r+') as f:
            l = f.readlines()
            l = [z for z in l if rem not in z]
        with open('names.txt', 'w') as f:
            f.writelines(l)

    elif name == "exit":
        r.close()
        exit()

• Removed NXT variable kept break to jump into next loop, second part of project.
• Added .close() to files to avoid problems saving, etc.
• Removed useless pieces of code that were left during building.
• Added .splitlines() to improve the accuracy of the users log in. And changed open for with open.
• Checked spaces between code like x=x and fixed readability.
• Changed name.lower() on every elif for name = name.lower()

Again thank you very much for the patience and help.