I am very new to Python (I've been learning it for about 2 weeks, in a
class). I wrote this function ( as part of a larger program, for my
homework) which is supposed to step through two given strings and check for
differences between the strings. It returns a list of the indices at which
the characters are different. Here it is:
def getDiff(word1,word2):
#this function takes two words and returns a list containing the index
of each point of difference in the words
difList = [] #creates empty list to hold index (location) of differences
in words
index = 0 #sets variable index to 0 to start
for item in word1: #steps throug string
if item == item in word2: #checks characters against each other
print "there is a match at index ", index
print word1[index]
print word2[index]
index += 1 #increments index
else:
print "they are not the same at index ", index
print word1[index]
print word2[index]
difList.append(index) #adds index value to list
index += 1 # increments index
return difList
It works, but only sometimes-- in some cases, it evaluates letters that are
different as being the same. Seems to be happening after a run of a few
matching letters? It also works for "carpet" "carrot", but not for "carrot"
"carpet". I think it must be something wrong with the structure of the
loop-- or how i am using it-- but I can't see it. Does anyone have any
suggestions? Here is output from some sample runs:
getDiff("desk","foot") # works fine
they are not the same at index 0
d
f
they are not the same at index 1
e
o
they are not the same at index 2
s
o
they are not the same at index 3
k
t
[0, 1, 2, 3]
getDiff("beep","bees") # works fine
there is a match at index 0
b
b
there is a match at index 1
e
e
there is a match at index 2
e
e
they are not the same at index 3
p
s
[3]
getDiff("freeze","fresia") # this one did not work!
there is a match at index 0
f
f
there is a match at index 1
r
r
there is a match at index 2
e
e
there is a match at index 3
e
s
they are not the same at index 4
z
i
there is a match at index 5
e
a
[4]
getDiff("carrot","carpet") # this one did not work!
there is a match at index 0
c
c
there is a match at index 1
a
a
there is a match at index 2
r
r
there is a match at index 3
r
p
they are not the same at index 4
o
e
there is a match at index 5
t
t
[4]
getDiff("carpet","carrot") #but this does work (inverted order from
above)
there is a match at index 0
c
c
there is a match at index 1
a
a
there is a match at index 2
r
r
they are not the same at index 3
p
r
they are not the same at index 4
e
o
there is a match at index 5
t
t
[3, 4]
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