Question

I keep getting this error:

line 4, in timesTwo 
IndexError: list index out of range

for this program:

def timesTwo(myList):
counter = 0
while (counter <= len(myList)):
    if myList[counter] > 0:
        myList[counter] = myList[counter]*2
        counter = counter + 1
    elif (myList[counter] < 0):
        myList[counter] = myList[counter]*2
        counter = counter + 1
    else:
        myList[counter] = "zero"
return myList

I’m not exactly sure how to fix the error. Any ideas?

Answer 1

You are setting the upper-bound of the while loop to the length of myList, which means that the final value of counter will be the length. Since lists are indexed starting at 0, this will cause an error. You can fix it by removing the = sign:

while (counter < len(myList)):

Alternatively, you could do this in a for loop that may be a bit easier to handle (not sure if this fits your use case, so the above should work if not):

def timesTwo(myList):

  for index, value in enumerate(myList):
    if value is not 0:
      myList[index] *= 2
    else:
      myList[index] = 'zero'

  return myList