Python 'if' And 'while' Conditions Not Working

I am writing a simple Python program. It's supposed to read two sorted lists from tab-delineated file and merge them into a single sorted list. The algorithm isn't too tough but Py

Solution 1:

You want and, not or, in your while loop test:

while i < len(list1) and j < len(list2):

(i < len(list1)) or (j < len(list2)) is going to be true if one of those tests is true. So i doesn't have to be smaller than len(list1) as long as j is smaller than len(list2). False or True is still True.

Next, your if test is most likely comparing strings, not integers. Strings are compared lexicographically:

>>> 'abc' < 'abd'True>>> 'ab' < 'b'True>>> '10' < '2'True

The first characters are compared before other characters are tested, and '1' sorts before '2'.

Compare integers instead:

if int(list1[i]) < int(list2[j]):

You probably want to convert your file inputs to integers the moment you read them, however.