Combining two strings to form a new string

Question

I am trying to write a program that asks the user for two strings and creates a new string by merging the two together (take one letter from each string at a time). I am not allowed to use slicing. If the user enters abcdef and xyzw, program should build the string: axbyczdwef

s1 = input("Enter a string: ")
s2 = input("Enter a string: ")
i = 0
print("The new string is: ",end='')
while i < len(s1):
    print(s1[i] + s2[i],end='')
    i += 1

The problem I am having is if one of the strings is longer than the other I get an index error.

Daniel · Accepted Answer · 2014-02-28 02:51:50Z

2

You need to do your while i < min(len(s1), len(s2)), and then make sure to print out the remaining part of the string.

OR

while i < MAX(len(s1), len(s2)) and then only print s1[i] if len(s1) > i and only print s2[i] if len(s2) > i in your loop.

answered Feb 28, 2014 at 2:51

Daniel

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Comments

Aaron Hall · Accepted Answer · 2014-02-28 06:44:55Z

1

I think zip_longest in Python 3's itertools gives you the most elegant answer here:

import itertools

s1 = input("Enter a string: ")
s2 = input("Enter a string: ")

print("The new string is: {}".format(
      ''.join(i+j for i,j in itertools.zip_longest(s1, s2, fillvalue=''))))

Here's the docs, with what zip_longest is doing behind the scenes.

edited Feb 28, 2014 at 6:44

answered Feb 28, 2014 at 3:03

Aaron Hall♦

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2 Comments

Daniel Over a year ago

Definitely a better answer than mine, though perhaps less inline with the educational goal of the assignment.

Aaron Hall Over a year ago

Danke Daniel! :) Oops, I left in her original i which was unused, thanks for bumping this for me. :)

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