Building a Simple ATM System in Python: A Casual Walkthrough

Hey everyone,

So, I wanted to share with you all how I put together this simple ATM system in Python. It's nothing fancy, but it gets the job done!

First off, I set up a couple of dictionaries to keep track of card numbers, PINs, and account balances. It looks something like this:

import time

# Dictionary to store card numbers and corresponding PINs
cardsWithPin = {123456789: 123, 987654321: 345, 234567890: 567, 345678901: 789}

# Dictionary to store card numbers and corresponding account balances
cardsWithAmt = {123456789: 50000, 987654321: 5000, 234567890: 7890, 345678901: 100000}

Then, I created functions for different operations like checking balance, withdrawing money, and depositing money. Here's a snippet of that:

# Function to check account balance
def checkBalance(cardNo):
    print(f"Current Balance: Rs.{cardsWithAmt.get(cardNo)}/-")
    time.sleep(0.6)

# Function to withdraw money
def withdraw(cardNo):
    print(f"Initial Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
    try: 
        withdrawAmt=int(input("Enter amount you want to withdraw: "))
        if(cardsWithAmt[cardNo]>=withdrawAmt):
            cardsWithAmt[cardNo]=cardsWithAmt.get(cardNo, 0)-withdrawAmt
            time.sleep(0.6)
            print(f"RS. {withdrawAmt}/- Withdraw Successfully...")
            print(f"Remaining Amount: Rs.{cardsWithAmt[cardNo]}/-")
            time.sleep(0.6)
        else:
            time.sleep(1)
            print("Insufficient Balance...")
            time.sleep(0.6)
    except ValueError:
        print("Please Enter Integer Value...")

# Function to deposit money
def deposit(cardNo):
    print(f"Initial Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
    try:
        dipositAmt=int(input("Enter amount you want to deposit:"))
        time.sleep(0.6)
        cardsWithAmt[cardNo] = cardsWithAmt.get(cardNo,0)+ dipositAmt
        print(f"Rs.{dipositAmt}/-are deposited successfully...")
        print(f"Current Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
        time.sleep(0.6)
    except ValueError:
        print("Please Enter Integer Value...")

# Main ATM system function
def atmSystem():
    # Some code here...

The atmSystem function is where the magic happens. It handles the whole ATM experience, from logging in to performing transactions and quitting the system.

def atmSystem():
    print("======================WELCOME==========================")
    # Some code here...

And that's pretty much it! It's a straightforward program that does what it's supposed to do. Of course, there's always room for improvement, but for now, I'm happy with how it turned out.

Feel free to take a look at the full code and play around with it. If you have any suggestions for improvements or cool features to add, I'm all ears!

Catch you later!

---

And here's the complete code:

import time
cardsWithPin={123456789:123,987654321:345,234567890:567,345678901:789}
cardsWithAmt={123456789:50000,987654321:5000,234567890:7890,345678901:100000}

def checkBalance(cardNo):
    print(f"Current Balance: Rs.{cardsWithAmt.get(cardNo)}/-")
    time.sleep(0.6)

def withdraw(cardNo):
    print(f"Initial Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
    try: 
        withdrawAmt=int(input("Enter amount you want to withdraw: "))
        if(cardsWithAmt[cardNo]>=withdrawAmt):
            cardsWithAmt[cardNo]=cardsWithAmt.get(cardNo, 0)-withdrawAmt
            time.sleep(0.6)
            print(f"RS. {withdrawAmt}/- Withdraw Successfully...")
            print(f"Remaining Amount: Rs.{cardsWithAmt[cardNo]}/-")
            time.sleep(0.6)
        else:
            time.sleep(1)
            print("Insufficient Balance...")
            time.sleep(0.6)
    except ValueError:
        print("Please Enter Integer Value...")



def deposit(cardNo):
    print(f"Initial Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
    try:
        dipositAmt=int(input("Enter amount you want to deposit:"))
        time.sleep(0.6)
        cardsWithAmt[cardNo] = cardsWithAmt.get(cardNo,0)+ dipositAmt
        print(f"Rs.{dipositAmt}/-are deposited successfully...")
        print(f"Current Balance:Rs.{cardsWithAmt.get(cardNo)}/-")
        time.sleep(0.6)
    except ValueError:
        print("Please Enter Integer Value...")

def atmSystem():
    print("======================WELLCOME==========================")
    try:
        cardNo=int(input("Enter your card number:"))
        if cardNo not in cardsWithPin:
            print("Invalid card no...")
            return
        pin=int(input("Enter pin: "))
        if cardsWithPin.get(cardNo)!=pin:
            print("Invalid pin...")
            return
    except ValueError:
        print("Card Number and Pin should always INTEGER")
        return
    time.sleep(0.5)
    print("Login Successfull...")
    time.sleep(0.4)

    while True: 
        print("""Please select any option:
            1).Deposit
            2).Withdraw
            3).Check Balance
            4).Quit
                """)
        operation=int(input("Select option: "))
        match(operation):
            case 1:
                print("You selected Money Deposit...")
                deposit(cardNo)
            case 2:
                print("You selected Withdraw...")
                withdraw(cardNo)
            case 3:
                print("You selected Check Balance...")
                checkBalance(cardNo)
            case 4:
                time.sleep(0.3)
                print("Thank you for using the ATM. Goodbye!")
                return
            case _: 
                print("Invalid option")
                time.sleep(0.6)

atmSystem()

Feel free to copy and paste it into your Python environment and give it a try! Let me know if you have any questions or suggestions.