calculator.py

"""A prefix-notation calculator."""


from arithmetic import *


while True:
    user_input = input("> ")
    tokens = user_input.split(" ")

    if "q" in tokens:
        print("You will exit.")
        break

    elif len(tokens) < 2:
        print("Not enough inputs.")
        continue

    operator = tokens[0]
    num1 = tokens[1]

    if len(tokens) < 3:
        num2 = "0"

    else:
        num2 = tokens[2]

    if len(tokens) > 3:
        num3 = tokens[3]

    # A place to store the return value of the math function we call,
    # to give us one clear place where that result is printed.
    result = None

    if not num1.isdigit() or not num2.isdigit():
        print("Those aren't numbers!")
        continue

    # We have to cast each value we pass to an arithmetic function from a
    # a string into a numeric type. If we use float across the board, all
    # results will have decimal points, so let's do that for consistency.

    elif operator == "+":
        result = add(float(num1), float(num2))

    elif operator == "-":
        result = subtract(float(num1), float(num2))

    elif operator == "*":
        result = multiply(float(num1), float(num2))

    elif operator == "/":
        result = divide(float(num1), float(num2))

    elif operator == "square":
        result = square(float(num1))

    elif operator == "cube":
        result = cube(float(num1))

    elif operator == "pow":
        result = power(float(num1), float(num2))

    elif operator == "mod":
        result = mod(float(num1), float(num2))

    elif operator == "x+":
        result = add_mult(float(num1), float(num2), float(num3))

    elif operator == "cubes+":
        result = add_cubes(float(num1), float(num2))

    else:
        result = "Please enter an operator followed by two integers."

    print(result)