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Python Python Basics (Retired) Putting the "Fun" Back in "Function" Functions

Richard Hummel
PLUS
Richard Hummel
Courses Plus Student 5,677 Points
Posted by Richard Hummel
Richard Hummel
Courses Plus Student 5,677 Points

Can't convert 'int' object to str implicitly...not sure what I'm doing wrong

I'm not sure what I'm doing wrong...I know I'm not converting the int properly to strings.

functions.py 
# add_list([1, 2, 3]) should return 6
def add_list(aList):
  for each in aList:
    total = sum(aList)
  return total
# summarize([1, 2, 3]) should return "The sum of [1, 2, 3] is 6."
def summarize(aList):
  X = " ".join(str(e) for e in aList)
  Y = add_list(aList)
  return "The sum of " + X + "is " + Y + "."
# Note: both functions will only take *one* argument each.

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,457 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

The error occurs in your return statement where it is trying to form a string from concatenation. This only works with items that are strings.

Since X is an int it needs to be converted directly using str() or through a format statement:

# using str()
return "The sum of " + str(X) + "is " + Y + "."
# using format()
return "The sum of {} is ".format(X) + Y + "."

Other issues with your code::

  • The Y value for a list [1, 2, 3] is "1 2 3". The challenge is looking for the string representation of the list "[1, 2, 3]". A list can be converted to a string directly also using str() or format()
  • missing space before "is "
# using str()
def summarize(aList):
  X = str(aList)
  Y = str(add_list(aList))
  return "The sum of " + X + " is " + Y + "." #<-- added missing space

# using format()
def summarize(aList):
  return "The sum of {X} is {Y}.".format(X=aList, Y=add_list(aList))

# which can be shortened to
def summarize(aList):
  return "The sum of {} is {}.".format(aList, add_list(aList))