python:Write a program that keeps reading positive numbers from the user

Question

hi i am very new to programming and was doing my 6th assignment when i started to draw a blank i feel as thou its really simple but i cant figure out how to continue and would appreciate some advice showing the correct code would be cool and all but i would really appreciate feed back along with it more so then what to do and if so where i went wrong down below is what im supposed to do.

Write a program that keeps reading positive numbers from the user. The program should only quit when the user enters a negative value. Once the user enters a negative value the program should print the average of all the numbers entered.

what im having trouble with is getting the number to remember okay user entered 55 (store 55) user entered 10 (store 10) user enter 5 (store 5) okay user put -2 end program and calculate. problem is its not remembering all previous entry's its only remembering the last input (which i guess is what my codes telling it to do) so how do i code it so that it remembers all previous entry's

and here is the code i have so far

number = 1
while ( number > 0):
   number = int(input("enter a number. put in a negative number to end"))
   if number > 0 :
      print (number)
   else:
      print (number) # these are just place holders 

Answer 1

If you really want to remember all previous entries, you can add them to a list, like so:

# before the loop
myList = []

# in the loop
myList = int(input("enter a number. put in a negative number to end"))

Then you can easily compute the mean of the numbers by iterating over the list and dividing by the length of the list (I'll let you try it yourself since its an assignment).
Or, if you want to save (a little) memory, you can add them each time to a variable and keep another variable for the count.

Answer 2

You can use a simple list in order to keep track of the numbers that have been inserted by the user. This list may then get processed in order to calculate the average when every number got read in ...

# This is a simple list. In this list we store every entry that
# was inserted by the user.
numbers = []

number = 1 
while ( number > 0):
   number = int(input("enter a number. put in a negative number to end "))
   if number > 0 :
      print (number)
      # save the number for later usage.
      numbers.append(number)

# calculate average
if len(numbers) == 0:
    print("You have not inputted anything. I need at least one value in order to calculate the average!")
else:
    print("The average of your numbers is: %s" % (sum(numbers) / len(numbers)))

Answer 3

What you need is an list which can store multiple values. It is often use with loops to insert/get value from it.

For instance,

number = 1
numbers = []
while ( number > 0):
    number = int(input("enter a number. put in a negative number to end"))
    if number > 0 :
        numbers.append(number)
print (numbers)

What you get is a list of numbers like [4, 10, 17] in ascending order as append() will add number to the back of the list. To get individual numbers out of the list:

numbers[0]

Note that the index inside the bracket starts from 0, so for instance you have a list with [4, 10, 17]. You should use the below 3 to get each of them:

numbers[0]
numbers[1]
numbers[2]

Or even better, with a loop.

for x in numbers:
    print (x)