Question

I am having some trouble finding the solution for the “Join all exercise” in the Hands-on Python Tutorial of Andrew N. Harrington.

Basically, the exercise is to take a list like ['very', 'hot', 'day'] consisting only of strings, and to make one string out of it, in this case 'veryhotday'.

This is the exercise:

'''exercise to complete and test this function'''
def joinStrings(stringList):
    '''Join all the strings in stringList into one string,
    and return the result, NOT printing it. For example:
    >>> s = joinStrings(['very', 'hot', 'day'])
    >>> print(s)  # I can print s OUTSIDE joinStrings
    'veryhotday'
    '''
    # finish the code for this function

def main():
    print(joinStrings(['very', 'hot', 'day']))
    print(joinStrings(['this', 'is', 'it']))
    print(joinStrings(['1', '2', '3', '4', '5']))

main()

So only the first definition may be changed. I solved it like this:

def joinStrings(stringList):
    return ''.join(stringList)

and I believe this works and is correct. Correct me if I am wrong here, but the problem is that it has to be solved differently. I have to sort of accumulate the different strings. just as they show here with integers:

def sumList(nums):
    ’’’Return the sum of the numbers in the list nums.’’’
    sum = 0
    for num in nums:
        sum = sum + num
    return sum

and really I just can’t figure it out, so please help me!

Answer 1

''.join(stringList) is the correct way. What is the problem?

If it has to be done differently, you could do one of:

import operator
return reduce(operator.add, stringList)

or even

s = ''
for string in stringList:
    s = s + string
return s

but that’s unnecessary complication, since using join like you suggested is the simplest and preferred way. Probably also the fastest.