如何在python上自行添加用户定义的函数？

Question

I'm not sure if it's possible or I misread the instruction for my homework but here's what I mean

def price():
    input("Please enter price of product: ")

price()
price()
price()

    def tot():
    #find the sum of the 3 values
tot()

So I called out the function price() three times to allow the use to enter 3 values. I would like to add up these 3 values in the function tot() but how can I do that when they have no labels? Do the parameters play a part here? It's an introductory course so I know very little and it was not explained. Here is the full question and how the output should be. As you can see it says call function 3 times

Image of assignment :

Answer 1

You need to store the user input somewhere so you can use it later. A simple way to do this is to store input values in a list.

Here's an example:

def get_price():
    raw_input = input("Please enter price of product: ")
    return int(raw_input)

def get_total(prices):
    # sum them up

def run():
    prices = []
    for _ in range(3): # three times
        new_price = get_price()
        prices.append(new_price)

    total_price = get_total()
    print(f"Total is ${total_price}")

Alternatively, (if you don't care about the individual prices after they've been entered) you could just keep a running total and add to it each time a user inputs a new price. The point is that you need to do something with the user input.

Answer 2

Functions can return a value. So if I define a function:

def getCheese():
    return "blue"

The output from that function (the part return acts on) can be assigned where the function is called:

my_cheese = getCheese()
print( my_cheese )  # prints "blue"

So for your question, you need to assign the returned result from python's built-in input() function, and then return that from your price() function. These returned values can then be stored in some other variables to tally up the prices.