python how to populate a list in loop

Question

I am trying to write a program that will receive inputs, run some calculations and store them in a list before adding the elements of the list. but I keep getting the error: wh_list = wh_list.append(wh) AttributeError: 'NoneType' object has no attribute 'append'

code:

wh_list = []
u = len(wh_list)
if u <= 1:
    while True:
        inp = input("Y or N:")
        B = int(input("B value:"))
        C = int(input("C value:"))
        D = int(input("D value:"))
        wh = B * C * D
        wh = int(wh)
        wh_list = wh_list.append(wh)
        if inp == "Y":
            break
else:
    Ewh = sum(wh_list)
    print(Ewh)

Please add a plain python tag, not just python-3.x – Mad Physicist Sep 11 '18 at 10:50 — Mad Physicist, Sep 11 '18 at 10:50

score 0 · Accepted Answer · answered Sep 11 '18 at 10:50

0

append changes the list and returns None. Thus,

wh_list = wh_list.append(wh)

will

append wh to wh_list
assign None to wh_list

In the next iteration, it will break, as wh_list is a list no more.

Instead, write just

wh_list.append(wh)

answered Sep 11 '18 at 10:50

Amadan

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Could you help me dupe hammer the question? – Mad Physicist Sep 11 '18 at 10:52
@MadPhysicist I did vote, when you posted the dupe... Not sure how to explicitly hammer it. – Amadan Sep 11 '18 at 10:53
I probably added the tag only after you voted. Oh well. Hopefully someone else will come along and do it. Thanks anyway. – Mad Physicist Sep 11 '18 at 10:54
@MadPhysicist Ah, that's probably it. – Amadan Sep 11 '18 at 10:58

python how to populate a list in loop

1 Answers1