Python Tutorial: How to Build Your First ATM Terminal
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Python is quite a resourceful language for anyone hoping to build incredible solutions in AI, FinTech, automation and so on.
You’ll find this tutorial impactful if you are a beginner or intermediate Pythonista. Basically, you will learn how to build an ATM terminal that works locally.
For maximal learning, ensure you code along and understand every line you write; that’s how to keep thickening your software engineering experience.
Step-by-step guide to Building Your First ATM Console with Python
This is the simple logic of the program:
customers should be able to create ATM pins the pins should be of 4 digits and digits only
customers should be able to login only with their created pin and nothing else
customers should be able to:
see their balances
withdraw
deposit
exit
Step 1: Creating ATM Pins
Authentication is crucial to any financial software. As a result, this program will demand customers or bank users to create ATM pins they will subsequently need to access their bank accounts.
def create_pin():
while True:
print("*******************************")
pin = input("Create a 4-digit PIN: ")
print("*******************************")
#@dev python doesn't support ||
if pin.isdigit() and len(pin) == 4:
print("*******************************")
print("PIN successfully created!")
print("*******************************")
return pin
print("*******************************")
print("Invalid PIN; enter exactly 4 digits.")
print("*******************************")
Here, we created the pin variable; ensured the length of the pin is not more than 4 with len(pin) == 4 and that it is only in digits [and not alphanumeric] with .isdigit.
Recall that Python does not support ||, hence the reason for using and.
Step 2: Accessing Bank Account with Created Pins
Once customers have created their pins once, they must use the same pin to access their accounts.
def login(pin):
password_inputing_chances = 3
while password_inputing_chances != 0:
print("*******************************")
entered_pin = input("Enter your 4-digit PIN: ")
print("*******************************")
if entered_pin == pin:
print("Login successful!")
return True
# upon every attempt, there is one reduction
password_inputing_chances -= 1
print(f"{password_inputing_chances} attempts left")
print("Account locked due to too many failed attempts.")
return False
We created a function that takes in pin as a parameter, and remember that pin has been declared earlier.
It is the case that customers only have 3 attempts to input their pins, after which they will be automatically bounced out of the ATM console.
Customers can input their pins while their password_inputing_chances is not zero. Meanwhile, they have 3 chances to input the correct pin, or else, they will be bounced out of the console.
The number of attempts is tracked with password_inputing_chances -= 1. Therefore, customers lose a chance out of their 3 chances when they input incorrect pins.
Step 3: Check Balance Function
def show_user_balance(balance):
print(f"Your balance is ${balance}")
This is a pretty straightforward code that prints customer balance. By the way, balance will be defined more properly later in the program.
Step 4: Deposit Function
def deposit():
amount = float(input("Input the amount you want to deposit: $"))
if amount <= 0:
print("No, you can't deposit an insignificant amount.")
return 0
return amount
In the deposit function above, we ensured that customers cannot deposit amounts less than or equal to 0 with if amount <= 0.
Step 5: Withdrawal Function
def withdraw_money(balance):
amount = float(input("Enter the amount of money you want to withdraw: $"))
if amount > balance:
print("You don't have sufficient funds for this.")
return 0
elif amount <= 0:
print("You can only withdraw more than $0.")
return 0
return amount
We created two important statements here:
customer cannot withdraw greater than their balances
they cannot withdraw 0 or anything less than it
Step 6: Main Function for Logic Definition
def main():
print("Welcome to Jubilee Bank!")
pin = create_pin()
if not login(pin):
return
balance = 0
customer_engagement_is_running = True
while customer_engagement_is_running:
print("\\n****************************")
print("1. Show Balance")
print("2. Deposit")
print("3. Withdraw")
print("4. Exit")
print("****************************")
choice = input("Please enter your choice between 1 and 4: ")
if choice == "1":
show_user_balance(balance)
elif choice == "2":
balance += deposit()
print("Deposit successful.")
elif choice == "3":
balance -= withdraw_money(balance)
print("Withdrawal successful.")
elif choice == "4":
customer_engagement_is_running = False
else:
print("Invalid choice, please pick between 1 and 4.")
print("Thank you for banking with us!")
# this makes our script run as the "main" program
if __name__ == "__main__":
main()
The first thing we did in the main function is to request customers create pin and only login with what they have created:
if not login(pin):
return
We set the global balance to 0.
Then we created a boolean variable called customer_engagement_is_running, such that when a customer is interacting with the ATM console, the logic will execute.
Customers have 4 choices:
know balance
withdraw
deposit
exit
We made the loop switch off whenever a customer wants to exit. With regards to deposit and withdrawal, we used -= and += to handle the decrementation and incrementation logic accordingly.
Finally, we included if __name__ == "__main__": main() so our main function can successfully execute.
Full Code
Here is the full code:
# ATM terminal Python program
# code logic:
# 1. customers should be able to create ATM pins
# the pins should be of 4 digits and digits only
# 2. customers should be able to login only with their created pin and nothing else
# 3. customers should be able to:
# * see their balances
# * withdraw
# * deposit
# *exit
# 4. we should use functions to make our code more readable
def create_pin():
while True:
print("*******************************")
pin = input("Create a 4-digit PIN: ")
print("*******************************")
#@dev python doesn't support ||
if pin.isdigit() and len(pin) == 4:
print("*******************************")
print("PIN successfully created!")
print("*******************************")
return pin
print("*******************************")
print("Invalid PIN; enter exactly 4 digits.")
print("*******************************")
def login(pin):
password_inputing_chances = 3
while password_inputing_chances != 0:
print("*******************************")
entered_pin = input("Enter your 4-digit PIN: ")
print("*******************************")
if entered_pin == pin:
print("Login successful!")
return True
# upon every attempt, there is one reduction
password_inputing_chances -= 1
print(f"{password_inputing_chances} attempts left")
print("Account locked due to too many failed attempts.")
return False
def show_user_balance(balance):
print(f"Your balance is ${balance}")
def deposit():
amount = float(input("Input the amount you want to deposit: $"))
if amount <= 0:
print("No, you can't deposit an insignificant amount.")
return 0
return amount
def withdraw_money(balance):
amount = float(input("Enter the amount of money you want to withdraw: $"))
if amount > balance:
print("You don't have sufficient funds for this.")
return 0
elif amount <= 0:
print("You can only withdraw more than $0.")
return 0
return amount
def main():
print("Welcome to Jubilee Bank!")
pin = create_pin()
if not login(pin):
return
balance = 0
customer_engagement_is_running = True
while customer_engagement_is_running:
print("\\n****************************")
print("1. Show Balance")
print("2. Deposit")
print("3. Withdraw")
print("4. Exit")
print("****************************")
choice = input("Please enter your choice between 1 and 4: ")
if choice == "1":
show_user_balance(balance)
elif choice == "2":
balance += deposit()
print("Deposit successful.")
elif choice == "3":
balance -= withdraw_money(balance)
print("Withdrawal successful.")
elif choice == "4":
customer_engagement_is_running = False
else:
print("Invalid choice, please pick between 1 and 4.")
print("Thank you for banking with us!")
# this makes our script run as the "main" program
if __name__ == "__main__":
main()
Testing
You can easily test the code in your terminal by writing this on your terminal:
python name.py
If you play around with it, you will have something like this:
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