So, I am very new to python. I am trying to learn some new code, and I want to learn how to do functions better. I have recently written a program that acts as a 'banking system'. I thought of a new challenge where I want to have multiple 'people' and their corresponding accounts/balances. I know that the best way to do this is a function, but I have a couple of problems. The first is that when I tentatively set the whole program to a function it gave me an error saying I didn't define "end" even though I did (see code below). The second is, that I don't know how to have the function use a different variable for each person (ie, if I want to be person 1, how do I make the function edit that variable and not person 2)? Would someone please explain this to me? Here is the code:

bal=500
lock=0
end=False

def atm():
    while end==False:
        if lock>=4:
            while lockloop==True:
                try:
                    print("Your balance is $",bal, sep='')
                    lk=int(input("Error, you have locked your account. Please enter funds until balance becomes positive: \n$"))
                    if lk<=0:
                        print("Please input a positive amount")
                        continue
                    bal=bal lk
                    if bal<0:
                        continue
                except ValueError:
                    print("Try again")
                    continue
                else:
                    lockloop=False
                lk=0
                lock=0
                print("Your balance is now: $", bal, sep='')
        des=input("Would you like to (d)eposit, (w)ithdraw, (b)alance, or (e)nd? ")
        witloop=True
        deploop=True
        lockloop=True
        if lock>1 and bal>=0:
            lock=1
        if des=="deposit" or des=="d" and lock<4:
            while deploop==True:
                try:
                    dep=int(input("How much would you like to deposit? "))
                    if dep<=0:
                        print("Please input a positive amount")
                        continue
                except ValueError:
                    print("Try again")
                    continue
                else:
                    deploop=False
                bal=dep bal
                dep=0
                if bal<0 and lock==0:
                    bal=bal-50
                    lock=lock 1
                    print("You have incured an overdraft fee of $50. It will be removed from your account.")
                if bal<0 and lock!=0:
                    lock=lock 1
                    print("Your account is still overdrawn. Please deposit funds.")
                print("You now have: $", bal, sep='')
                continue
        elif des=="withdraw" or des=="w" and lock<4:
            if bal<=0:
                print("Cannot withdraw funds at this time.")
                continue
            while witloop==True:
                try:
                    wit=int(input("How much would you like to withdraw? "))
                    if wit<=0:
                        print("Please input a positive amount")
                        continue
                except ValueError:
                    print("Try again")
                    continue
                else:
                    witloop=False
            bal=bal-wit
            wit=0
            if bal<0 and lock==0:
                bal=bal-50
                lock=lock 1
                print("You have incured an overdraft fee of $50. It will be removed from your account.")
            if bal<0 and lock!=0:
                lock=lock 1
                print("Your account is still overdrawn. Please deposit funds.")
            print("You now have: $", bal, sep='')
            continue
        elif des=="balance" or des=="b":
            print("You have: $", bal, sep='')
            continue
        elif des=="end" or des=="e" and lock==0:
            end=True
            print("Thank you for banking with Nolan's Banking Services today! Have a great day! :)")
        else:
            print("You must enter one of the four options, try again")
            continue
atm()

CodePudding user response：

Running your code as-is is returning this error:

UnboundLocalError: local variable 'end' referenced before assignment

The reason here is to do with the scope of your variables. You are declaring the bal, lock and end variables outside of your function, therefore making them global variables. But you are also then declaring those variables inside the function, making them local variables. The interpreter is getting confused and the error is telling you the the local variable end is being used before it is being assigned.

Don't mix and match variables inside and outside a function like this.

You could read some more here as a starting point:

https://www.w3schools.com/python/python_variables_global.asp

https://bobbyhadz.com/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment

I don't know how to have the function use a different variable for each person

You can pass arguments into your function like this. In this case, when we define the function, we tell it to expect an argument called user that you can then use inside your function.

def atm(user):
     if user == 'Nolan':
          print('Hi Nolan')

      elif user == 'Lummers':
          print('Hi Lummers')

     else:
          print("I don't talk to strangers")

atm('Nolan')
atm('Lummers')
atm('John Doe')