calculator.py

# A simple calculator class that performs basic arithmetic operations and keeps a history of calculations in a file.
class Calculator:
    def __init__(self):
        with open("history.txt", "w") as f:
            f.write("")  # Clear history on initialization
        self.history = []

    def add(self, a, b):
        result = a + b
        with open("history.txt", "a") as f:
            f.write(f"Added {a} and {b}: {result}\n")
        self.history.append(f"Added {a} and {b}: {result}")
        return result

    def subtract(self, a, b):
        result = a - b
        with open("history.txt", "a") as f:
            f.write(f"Subtracted {b} from {a}: {result}\n")
        self.history.append(f"Subtracted {b} from {a}: {result}")
        return result

    def multiply(self, a, b):
        result = a * b
        with open("history.txt", "a") as f:
            f.write(f"Multiplied {a} and {b}: {result}\n")
        self.history.append(f"Multiplied {a} and {b}: {result}")
        return result

    def divide(self, a, b):
        if b == 0:
            self.history.append(f"Attempted to divide {a} by zero: Error")
            return "Error: Division by zero"
        result = a / b
        with open("history.txt", "a") as f:
            f.write(f"Divided {a} by {b}: {result}\n")
        self.history.append(f"Divided {a} by {b}: {result}")
        return result

    def get_history(self):
        return self.history
    
# Example usage
if __name__ == "__main__":
    calc = Calculator()
    print(calc.add(5, 3))        # Output: 8
    print(calc.subtract(10, 4))  # Output: 6
    print(calc.multiply(2, 7))   # Output: 14
    print(calc.divide(20, 5))    # Output: 4.0
    print(calc.divide(10, 0))    # Output: Error: Division by zero
    print("\nHistory:")
    for entry in calc.get_history():
        print(entry)
    print("\nHistory from file:")
    with open("history.txt", "r") as f:
        print(f.read())
    # Interactive command loop to perform calculations and log history, also gives the option to clear history after each command.
    while True:
        command = input("Enter a command (add, subtract, multiply, divide) followed by two numbers: ")
        parts = command.split()
        with open("history.txt", "a") as f:
            f.write(f"Command entered: {command}\n")
            if len(parts) == 3:
                operation, num1, num2 = parts[0], float(parts[1]), float(parts[2])
                if operation == "add":
                    f.write(f"Performing addition: {num1} + {num2} = {calc.add(num1, num2)}\n")
                    print(calc.add(num1, num2))
                elif operation == "subtract":
                    f.write(f"Performing subtraction: {num1} - {num2} = {calc.subtract(num1, num2)}\n")
                    print(calc.subtract(num1, num2))
                elif operation == "multiply":
                    f.write(f"Performing multiplication: {num1} * {num2} = {calc.multiply(num1, num2)}\n")
                    print(calc.multiply(num1, num2))
                elif operation == "divide":
                    f.write(f"Performing division: {num1} / {num2} = {calc.divide(num1, num2)}\n")
                    print(calc.divide(num1, num2))
                else:
                    print("Unknown operation")
            else:
                print("Invalid command format")
        clear_history = input("Do you want to clear the history? (yes/no): ")
        if clear_history.lower() == "yes":
            with open("history.txt", "w") as f:
                f.write("")
                f.close()
        continue_input = input("Do you want to continue? (yes/no): ")
        if continue_input.lower() != "yes":
            print("Goodbye! See you next time.")
            break