jython - Finding length of list without using the 'len' function in python -

in high school assignment part of make function find average number in list of floating points. can't use len , such sum(numlist)/float(len(numlist)) isn't option me. i've spent hour researching , racking brain way find list length without using len function, , i've got nothing hoping either shown how or pointed in right direction. me stack overflow, hope. :)

use loop add values list, , count them @ same time:

def average(numlist):     total = 0     count = 0     num in numlist:         total += num         count += 1      return total / count 

if might passed empty list, might want check first , either return predetermined value (e.g. 0), or raise more helpful exception zerodivisionerror you'll if don't checking.

if you're using python 2 , list might integers, should either put from __future__ import division @ top of file, or convert 1 of total or count float before doing division (initializing 1 of them 0.0 work).