Building a Continuous Terminal Calculator in Python

Hello DEV Community 👋

I am currently diving deep into Python, focusing on strengthening my core programming logic. Today, I built a simple yet effective Terminal-Based Calculator.

While a basic calculator is a common beginner project, I wanted to ensure it didn't just run once and abruptly stop. I wanted it to feel like an actual software program.

✨ What I Built

A command-line calculator that performs basic arithmetic operations (Addition, Subtraction, Multiplication, Division) and continuously runs until the user explicitly commands it to stop.

🧠 The Core Logic: The while Loop

The game-changer for this project was wrapping the main logic inside an infinite while True: loop. Instead of the terminal closing after one calculation, the program loops back, asking the user for their next operation.

Here is how I structured the workflow:

1. User Menu: Display options (1 to 5).
2. Exit Condition: If the user selects '5', a break statement gracefully exits the loop.
3. Error Handling: Used a try-except block to catch ValueError just in case someone types a letter instead of a number. I also added a condition to prevent ZeroDivisionError.

💻 The Code

Here is the complete code for my calculator:

python
def start_calculator():
    print("--- Python Terminal Calculator ---")

    while True:
        print("\nOperations:")
        print("1. Add (+)")
        print("2. Subtract (-)")
        print("3. Multiply (*)")
        print("4. Divide (/)")
        print("5. Exit")

        choice = input("Select an operation (1/2/3/4/5): ")

        if choice == '5':
            print("Shutting down... Goodbye! 👋")
            break

        if choice in ('1', '2', '3', '4'):
            try:
                num1 = float(input("Enter first number: "))
                num2 = float(input("Enter second number: "))
            except ValueError:
                print("Error! Please enter valid numbers only.")
                continue  

            if choice == '1':
                print(f"Result: {num1} + {num2} = {num1 + num2}")

            elif choice == '2':
                print(f"Result: {num1} - {num2} = {num1 - num2}")

            elif choice == '3':
                print(f"Result: {num1} * {num2} = {num1 * num2}")

            elif choice == '4':
                if num2 != 0:
                    print(f"Result: {num1} / {num2} = {num1 / num2}")
                else:
                    print("Math Error! Cannot divide by zero.")
        else:
            print("Invalid Input! Please select a valid option.")

if __name__ == "__main__":
    start_calculator()