Python ATM Code for Account Balance, Withdraw, and Deposit Functions

Table of Contents

In this Python tutorial, we will look into some basic, common functions when using an ATM machine. The first step is to brainstorm what do you do at an ATM machine?

ATM Function Requirements

Some of the functions that one can complete at an ATM are below:

Input user pin for authentication
Check account balance
Deposit funds
Withdraw funds
Create random generated transaction id
Account interest rate and monthly accrued interest rate

Import Python Modules

In order to complete the above ATM, we will need to import two Python modules; numpy and random.

Python NumPy Module

What does the NumPy module do in Python?

The Python package NumPy is a fundamental package that has the unique capabilities for scientific computing. In addition, it offers the below as well:

N-dimensional array object
Sophisticated functions
Random number capabilities, useful for linear algebra, and Fourier transform

Besides the obvious scientific uses, NumPy also offers an efficient multi-dimensional container of generic data. This allows arbitrary data-types can be defined and will NumPy to speedily and efficiently integrate with a wide variety of databases.

Python Random Module

What does the Random package do in Python?

The Random module allows a program to create random numbers by using the random.randint() function. If we wanted a random integer, we can use the randint function and it will accept two parameters of numbers (lowest and highest).

1 2	import random import numpy

Create Class and Define Functions

What is a class?

A class is used for creating objects. By creating objects, the objects have variables and a behavior that’s associated with them. Since we are using Python in this tutorial, a class is created by a keyword class. Once the class is created, the object within the class will then be called the instance of the class.

How to define a function?

Now we take the requirements that we created from the above and create functions. We can define the functions to provide the given functionality of the program. The function blocks are started with def and followed with the function name and parenthesis, such as def getId(self).

class Account:

# Construct an Account object

def __init__(self, id, balance = 0, annualInterestRate = 3.4):

self.id = id

self.balance = balance

self.annualInterestRate = annualInterestRate

def getId(self):

return self.id

def getBalance(self):

return self.balance

def getAnnualInterestRate(self):

return self.annualInterestRate

def getMonthlyInterestRate(self):

return self.annualInterestRate / 12

def withdraw(self, amount):

self.balance -= amount

def deposit(self, amount):

self.balance += amount

def getMonthlyInterest(self):

return self.balance * self.getMonthlyInterestRate()

Define the main() Function

We must create the main() function because it’s only executed when the Python program is executed. Also, we could import a Python program as a module, but the main() method will not execute. The entry point of any program is the main() function, but the interpreter of python will execute the source file code sequentially. In addition, it will not call any method if it’s not within the code. This is why the main() method has a technique, so that the main() method will be executed when the program is executed directly and not when the module is imported.

By creating the main() method, we will use a range to have all users to enter a 4-digit pin to access their account.

def main():

# Creating accounts

accounts = [];

for i in range(1000, 9999):

account = Account(i, 0);

accounts.append(account);

ATM Process Creation Using while True

We will use the while True loop because it will loop forever. The while statement will take an expression and execute the body of the loop while the expression is equal to ‘boolean’ of True. As long as the loop stays True, the loop will indefinitely loop.

# ATM Processes

while True:

# Reading id from user

id = int(input("\nEnter account pin: "));

# Loop till id is valid

while id < 1000 or id > 9999:

id = int(input("\nInvalid Id.. Re-enter: "));

# Iterating over game

while True:

# Printing menu

print("\n1 - View Balance \t 2 - Withdraw \t 3 - Deposit \t 4 - Exit ");

# Reading selection

selection = int(input("\nEnter your selection: "));

# Getting account object

for acc in accounts:

# Comparing account id

if acc.getId() == id:

accountObj = acc;

break;

# View Balance

if selection == 1:

# Printing balance

print(accountObj.getBalance());

# Withdraw

elif selection == 2:

# Reading amount

amt = float(input("\nEnter amount to withdraw: "));

ver_withdraw = input("Is this the correct amount, Yes or No ? " + str(amt) + " ");

if ver_withdraw == "Yes":

print("Verify withdraw");

else:

break;

if amt < accountObj.getBalance():

# Calling withdraw method

accountObj.withdraw(amt);

# Printing updated balance

print("\nUpdated Balance: " + str(accountObj.getBalance()) + " \n");

else:

print("\nYou're balance is less than withdrawl amount: " + str(accountObj.getBalance()) + " \n");

print("\nPlease make a deposit.");

# Deposit

elif selection == 3:

# Reading amount

amt = float(input("\nEnter amount to deposit: "));

ver_deposit = input("Is this the correct amount, Yes, or No ? " + str(amt) + " ");

if ver_deposit == "Yes":

# Calling deposit method

accountObj.deposit(amt);

# Printing updated balance

print("\nUpdated Balance: " + str(accountObj.getBalance()) + " \n");

else:

exit();

elif selection == 4:

print("\nTransaction is now complete.");

print("Transaction number: ", random.randin

(10000, 1000000));

print("Current Interest Rate: ", accountObj.annualInterestRate);

print("Monthly Interest Rate: ", accountObj.annualInterestRate / 12);

print("Thanks for choosing us as your bank");

exit();

#break;

# Any other choice

else:

print("\nThat's an invalid choice.");

#break;

# Main function

main()

I hope this Python tutorial on creating an ATM program for checking account balance, withdrawing funds, and depositing funds was helpful.

Python ATM Code for Account Balance, Withdraw, and Deposit Functions

ATM Function Requirements

Import Python Modules

Python NumPy Module

What does the NumPy module do in Python?

Python Random Module

What does the Random package do in Python?

Create Class and Define Functions

What is a class?

How to define a function?

Define the main() Function

ATM Process Creation Using while True

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