Python 3：在字典中求和

Question

This is the question on my homework

Below is my attempt on solving it:

def printStocks(d):
for key, value in d.items() :
    print(key, "\tPrice: ", value[0], "\tAmount: ", value[1])
    sum_items = 0
    sum_items += value[0]*value[1]
print("Total value of all items: ", sum_items)
    
d_1 = {"banana": [4, 5], "apple": [2, 2], "orange": [1.5, 2.5], "pear": [3, 4]}

printStocks(d_1)

Although the Debug is this:

Part-2
banana  Price:  4   Amount:  5
apple   Price:  2   Amount:  2
orange  Price:  1.5     Amount:  2.5
pear    Price:  3   Amount:  4
Total value of all items:  12

So the problem is that the total value of all items should be 39.75

Since: 4x5 + 2x2 + 1.5x2.5 + 3x4 = 39.75;

I don't understand why it says 12 as the sum_items value. I am lost right now, could get some little help here. Thanks in advance.

Answer 1

You need to put your sum = 0 out of loop. In other case it will be zero after every iteration

Answer 2

You reinitialize the sum_items variable in each loop in for-loop. You should put the sum_items = 0 outside the for-loop.