calculator.py

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

def multiply(a, b):
    return a * b

def divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
        return "Error: Cannot divide by zero!"

def main():
    while True:
        print("\n===== SIMPLE CALCULATOR =====")
        print("1. Add")
        print("2. Subtract")
        print("3. Multiply")
        print("4. Divide")
        print("5. Exit")

        choice = input("Enter choice (1/2/3/4/5): ")

        if choice == '5':
            print("Exiting calculator. Goodbye!")
            break

        try:
            num1 = float(input("Enter first number: "))
            num2 = float(input("Enter second number: "))
        except ValueError:
            print("Invalid input! Please enter numbers only.")
            continue

        if choice == '1':
            print(f"Result: {add(num1, num2)}")
        elif choice == '2':
            print(f"Result: {subtract(num1, num2)}")
        elif choice == '3':
            print(f"Result: {multiply(num1, num2)}")
        elif choice == '4':
            print(f"Result: {divide(num1, num2)}")
        else:
            print("Invalid choice. Please try again.")

if __name__ == "__main__":
    main()