learn_python_extras

full_calculator.py

# This time let's not use a string for the operation parameter.
# Since it's an either-or choice, a Boolean will do nicely.

# For an explanation of the use of the "*" in the definition block, see
# https://ivergara.github.io/boolean-arguments-to-functions-in-python.html

def calculate(x: int, y: int = 1, *, subtract: bool = False) -> int:
    """Calculates the sum (or difference) of two numbers.

    Parameters:
    `x` : int
        The first number
    `y` : int, optional
        The second number (default is 1)
    `subtraction`: bool, optional
        Whether to perform subtraction. Default is False.
    """

    if subtract:
        return x - y
    else:
        return x + y


# Get two inputs from the user and cast them to integers
first = int(input("Enter a number: "))
second = int(input("Enter another number: "))


def ask_for_operation():
    user_choice = input("Do you want to subtract? (y/n): ")
    # Convert to lowercase (for comparison later)
    user_choice = user_choice.casefold()
    return user_choice


# Ask if they want subtraction; False by default
subtract_chosen = False
user_choice = ask_for_operation()
first_letter = user_choice[0]

while first_letter != "n" or "y":
    print("Sorry, your answer needs to start with a 'y' or an 'n'; please try again.")
    user_choice = ask_for_operation()

if first_letter == "y":
    subtract_chosen = True
    operation = "minus"
elif first_letter == "n":
    subtract_chosen = False
    operation = "plus"


# Print the results of the two calculations
result = calculate(first, second, subtract=subtract_chosen)
print(f"{first} {operation} {second} is {result}")

# If you don't pass a second variable, the default value is used:
result = calculate(first, subtract=subtract_chosen)
print(f"{first} {operation} the default value is {result}.")