CODEWITHSUNDEEP
python
Berk Ersoy
Berk Ersoy

Reputation: 43

Cant solve pre-beginner level python exercise

I am just learning python and using codecademy to learn basics but im stuck in an exercise, hoping you guys could hep with.

The course first wants me to define a function called compute_bill and give it one arguement which is food. Then give total an initial value of 0 and then for each item in food list add their value to total and finally return total.

this is the prewritten list of prices and stock numbers.

shopping_list = ["banana", "orange", "apple"]

stock = {
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}

prices = {
    "banana": 4,
    "apple": 2,
    "orange": 1.5,
    "pear": 3
}

and this is the little function that i wrote but course is not accepting it saying compute_bill(['apple']) resulted in a TypeError: unsupported operand type(s) for +=: 'int' and 'str' 

def compute_bill(food):
    total = 0
    for item in food:
        total += item
    return total

it might be a very stupid question for most of you but i just cant understand what's the problem with it.

Upvotes: 2

Views: 147

Answers (5)

Castiell
Castiell

Reputation: 167

def compute_bill(food) :
    total = 0
    for item in food :
        if stock[item] != 0 :
            total = total + prices[item]
            #you also need to update the stock table i won't do it here
    return total

food = {"banana","apple","orange"}
print compute_bill(food)

Upvotes: 0

Berk Ersoy
Berk Ersoy

Reputation: 43

I wish i could give you all an upvote. Thanks a lot for answers and advices i've just seen how silly i am.

def compute_bill(food):
    total = 0
    for key in food:
        total += prices[key]
    return total

this just did the trick

Upvotes: 1

Ashalynd
Ashalynd

Reputation: 12563

You are making a couple of mistakes:

1) "food" is a list. Every element there is a string. You can't add a string to a number in Python (and it wouldn't make sense).

2) What you really want to do is to use elements from "food" as keys, and then get prices from "prices" which is a dictionary.

One hint: to get a value for an element 'apple' from prices, you have to do something like:

apple_price = prices['apple']

This will give you the entry from 'prices' stored under the key 'apple', which is an integer equal 2. You can use this price to calculate the total.

Another hint: iterate over the elements in "food" and use these elements to retrieve corresponding prices from "prices" dictionary.

Good luck :)

Upvotes: 2

gngrwzrd
gngrwzrd

Reputation: 6012

You almost have it. The for loop is iterating through each string in the food[] array, with that string you need to lookup the price in the prices dictionary.

def compute_bill(food):
    total = 0
    for key in food:
        total += prices[key]
    return total

Upvotes: 1

Mikko Ohtamaa
Mikko Ohtamaa

Reputation: 83418

Try:

 total += prices[item]

The code in the question is not referring to prices at all.

Upvotes: 0

Related Questions