[Tutor] Need help adding a funcation

[Michael Hall]

I am still not understanding what it is I am being asked to do. What is the
differance between my_list = [] an my_list[ ] because when I use my_list[]
I get an error. Not sure what I am doing wrong. I am asking if you are
given the following question how would you write the program. I have most
of it.  Here is what I know works
# Create main function.
def main():
    a = input('Please Enter a Number: ') # Ask user for input.
    number = int(a)
    x = 1
    sum_of = 0
    getDivisors
    while number > x:
        if number % x == 0:
            sum_of = sum_of + x
        x += 1
    if sum_of == number:
       print(number,'is a Perfect Number')
    elif sum_of < number:
       print(number,'is a Non-perfect Number')
def getDivisors(num):
    sum = 0
    x = 1
    #my_list[] = num
    for num in range(1, num, 1):

        if num % x == 0:
            print(num)
            sum += num

    print('The sum is ', sum)
    if sum == num:
        print(num, 'is a perfect number')
    else:
        print(num, 'is not a perfect number')

main()

This is what the teacher is asking for:
# 1) a perfect number is a positive integer that is equal to the
# sum of its proper positive divisors,excluding the number itself.
# for example, 6 is a perfect number because it is evenly divisible
# by 1, 2 and 3 - all of it's divisors - and the sum 1 + 2 + 3 = 6.
# a) write a function, getDivisors(), that returns a list of all
# of the positive divisors of a given number. for example -
# result = getDivisors(24)
# print(result)
# would yield: "[ 1, 2, 3, 4, 6, 8, 12]"
# b) write a program that uses your function to determine which
# numbers between 1 and 10,000 are perfect. (answer: 6, 28, 496
# and 8128 are perfect!)

I am asking for help writing it. I am new to programming. Lost alot of
brain matter.
On Thu, Dec 1, 2011 at 3:22 PM, Alan Gauld <alan.gauld at btinternet.com>wrote:

> On 01/12/11 21:17, Michael Hall wrote:
>
>> Can anyone else help with this question?
>>
>
> Sure lots of us could help. But Dave's doing a good job
> leading you in the right direction.
>
> Is there something that you don't understand? If you ask about specific
> points we can give specific answers. Meantime I'll add a few extra comments
> to see if that helps...
>
>
>        def main():
>>             x = 1
>>
>>             num = int(input('Please Enter a Number: '))
>>             getDivisors(num)
>>
>>
>>    You'll want to store the return value of getDivisors, since you have
>>    more work to do there.
>>
>
> What Dave means is that you are simply calling the function but not
> storing the result. So you calculate the divisors but then have no chance
> to use them. You need to store them in a variable someplace.
> Think about the input() function you use above.
>
> If you had just done
>
>
>              int(input('Please Enter a Number: '))
>
> You couldn't use the value that the user entered.
> You had to assign it to num to do that. It's the same
> with your function getDivisors()
>
>
>        def getDivisors(num):
>>             sum = 0
>>             x = 1
>>             #my_list[] = num
>>
>>    That's close.  To create an empty list, simply do
>>            my_list = []
>>
>
> self explanatory, I hope.
>
>
>
>             for num in range(1, num, 1):
>>
>>                 if num % x == 0:
>>                     print(num)
>>                     sum += num
>>
>>    Why are you summing it?  That was in another function.  In this one,
>>    you're trying to build a list.  Any ideas how to do that at this
>>    point in the function?
>>
>
> So you need to store your results as a list not as a number. So instead of
> sum() what can you do to my_list to add a new element?
> If you aren't sure fire up the Python >>> prompt and try
> help(list) or  just help([]) and see if you can see anything useful.
>
>
>             print('The sum is ', sum)
>>             if sum == num:
>>                 print(num, 'is a perfect number')
>>             else:
>>                 print(num, 'is not a perfect number')
>>
>>    None of these lines belong in your function.  All it's supposed to
>>    do is get the divisors, not to study them in any way.
>>
>
> This is a good principle to apply when writing functions. Separate out the
> display from the logic. That way you can use the results of the logic with
> any kind of user interface - GUI, Web, or command line, or even in a server
> process without a UI.
>
> But this takes us back to the advice to assign the result to a variable in
> main().
>
> To do that you need to return a result. And in this case your result
> should be a list of numbers. then you can do any printing in the main
> function.
>
> HTH,
>
> --
> Alan G
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
>
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