Bank ATM program in Python

Question

For homework, I have to code a program in Python that effectively simulates a bank ATM.

print('Welcome to Northen Frock Bank ATM')
restart=('Y')
chances = 3
balance = 67.14
while chances >= 0:
 pin = int(input('Please Enter You 4 Digit Pin: '))
 if pin == (1234):
 print('You entered you pin Correctly\n')
 while restart not in ('n','NO','no','N'):
 print('Please Press 1 For Your Balance\n')
 print('Please Press 2 To Make a Withdrawl\n')
 print('Please Press 3 To Pay in\n')
 print('Please Press 4 To Return Card\n')
 option = int(input('What Would you like to choose?'))
 if option == 1:
 print('Your Balance is £',balance,'\n')
 restart = input('Would You you like to go back? ')
 if restart in ('n','NO','no','N'):
 print('Thank You')
 break
 elif option == 2:
 option2 = ('y')
 withdrawl = float(input('How Much Would you like to 
withdraw? \nÂ10ドル/Â20ドル/Â40ドル/Â60ドル/Â80ドル/Â100ドル for other enter 1: '))
 if withdrawl in [10, 20, 40, 60, 80, 100]:
 balance = balance - withdrawl
 print ('\nYour Balance is now £',balance)
 restart = input('Would You you like to go back? ')
 if restart in ('n','NO','no','N'):
 print('Thank You')
 break
 elif withdrawl != [10, 20, 40, 60, 80, 100]:
 print('Invalid Amount, Please Re-try\n')
 restart = ('y')
 elif withdrawl == 1:
 withdrawl = float(input('Please Enter Desired amount:')) 
 elif option == 3:
 Pay_in = float(input('How Much Would You Like To Pay In? '))
 balance = balance + Pay_in
 print ('\nYour Balance is now £',balance)
 restart = input('Would You you like to go back? ')
 if restart in ('n','NO','no','N'):
 print('Thank You')
 break
 elif option == 4:
 print('Please wait whilst your card is Returned...\n')
 print('Thank you for you service')
 break
 else:
 print('Please Enter a correct number. \n')
 restart = ('y')
 elif pin != ('1234'):
 print('Incorrect Password')
 chances = chances - 1
 if chances == 0:
 print('\nNo more tries')
 break

This program basically does what it is designed to do, but I want to learn how to use the def() and do it this way.

• user93231: this program didnot run it is syntax error in elif option==2:

Answer 1

The best way to do this would be to take each of your sections, and give them each a function of their own. Also, when it's possible, separate user input functions from purely logic to improve readability!

For example, it could start looking like this:

def verify_pin(pin):
 if pin == '1234':
 return True
 else:
 return False
def log_in():
 tries = 0
 while tries < 4:
 pin = input('Please Enter Your 4 Digit Pin: ')
 if verify_pin(pin):
 print("Pin accepted!")
 return True
 else:
 print("Invalid pin")
 tries += 1
 print("To many incorrect tries. Could not log in")
 return False
def start_menu():
 print("Welcome to the atm!")
 if log_in():
 # you will need to make this one yourself!
 main_menu()
 print("Exiting Program")
start_menu()

Whenever you can avoid nesting, you should. This makes it easier to read.

In this case you can clearly see logging in will open the main_menu (which you will have to write), and entering a correct pin is the only way to log in.