[Tutor] Question

[Alan Gauld]

On 03/12/11 08:31, Michael Hall wrote:

> # a) write a function, getDivisors(), that returns a list of all
> # of the positive divisors of a given number.

This is a very clear statement of what you need to do.

> def getDivisors(num):
>      my_list = []
>      sum = 0
>      for number in range(1, num, 10000):
>
>          if num % number == 0:
>              print([1, 2, 3])
>              sum += num
>
>      print('The sum is ', sum)
>      if sum == num:
>          print(num, 'is a perfect number')
>      else:
>          print(num, 'is not a perfect number')

> problem. If you enter the number 6 the program is just what the teacher
> wants. My problem is if you enter any other number it is wrong.

Even for 6 it is NOT what the teacher wants.
Your function PRINTS the answer the teacher asked for a function that 
RETURNS the answer. These are different things.
Do you understand the difference?

Also the reason it works for 6 is because you hard coded the answer for 6:

 >          if num % number == 0:
 >              print([1, 2, 3])

You only ever print [1,2,3]. You are not finding the divisors you are 
just printing [1,2,3].

Similarly the teacher did not ask you to test/report whether the number 
was perfect in the function, only to get the list of divisors. You need 
to strip the function back to the minimum to do what you were asked to do.

def getDivisors(num):
     my_list = []
     for x in range (1,num):
        # if is x a divisor of num
        #     add x to my_list
     return my_list

I've left the commented lines for you to complete.

But that is ALL you need for part (a) of the assignment.

You might need a main() function to test it, but it will simply print 
the result. Something like:

def main():
    print getDivisors(24)


As it is you are trying to do way too much and making your function more 
complicated than it needs to be. You can tweak it to make it more 
efficient later, but for now stick to the simplest thing that can 
possibly work and solve the problem you were asked to solve.

Once you have part (a) working part (b) of the assignment becomes easy.
But get (a) working before attempting (b). At the moment you are mixing 
the two together and making it more difficult. And that is one of the 
lessons from the homework. In programming, if you split a task down into 
smaller chunks it becomes easier. If you try to solve everything in one 
place it is much harder.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/