Unexpected output in python program

Question

I have copied the following code with some alteration in naming to solve the problem as stated: Given a string s, return a string where all occurences of its first char have been changed to '*', except do not change the first char itself. e.g. 'babble' yields 'ba**le'. Assume that the string is length 1 or more. Here is the code: My question is when I pass "Lulla" why don't I see "Lu**a" returned in the interpreter as I think the code should do.

def fix_start(s):
    start_letter = s[0]
    rest_letters = s[1:]
    rest_letters = rest_letters.replace(start_letter,'*')  
    return start_letter + rest_letters

print (fix_start ('Lulla'))

since your replacing with Captial L but others r small l

sundar nataraj
– sundar nataraj

2014-07-07 04:52:13 +00:00
Commented Jul 7, 2014 at 4:52 — sundar nataraj
– sundar nataraj, Commented Jul 7, 2014 at 4:52

Community · Accepted Answer · 2017-05-23 10:32:22Z

1

What happens is that Python is case-sensitive. In other words:

'L' != 'l'

So, when you do

rest_letters = rest_letters.replace(start_letter,'*')

it will replace all occurences of only L, not both L and l.

What can you do? The process of case-insensitive replacing is kind of complex, as you can see in these answers. But in your case, this may work:

rest_letters = rest_letters.replace(start_letter,'*').replace(start_letter.lower(), '*')

edited May 23, 2017 at 10:32

CommunityBot

11 silver badge

answered Jul 7, 2014 at 4:51

Christian Tapia

34.2k7 gold badges58 silver badges73 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

John La Rooy Over a year ago

What about "luLLa"? You should use start_letter.upper() to cover that possibility

l'L'l · Accepted Answer · 2014-07-07 05:13:13Z

0

Quite simply all that is required is to use lower() or upper() to change the string case:

start_letter = s[0].lower()
rest_letters = s[1:].lower()

Input: LulLa
Output: lu**a

answered Jul 7, 2014 at 5:13

l'L'l

47.5k12 gold badges102 silver badges154 bronze badges

2 Comments

John La Rooy Over a year ago

I think this is an odd interpretation. For some reason I assumed the case of the first letter shouldn't be changed in the output.

l'L'l Over a year ago

@gnibbler, Valid point; I interpreted the question/issue as how to match the word (regardless of case). The first character case could always be switched back after the match to retain that of the original return s[0] + rest_letters.

siddk · Accepted Answer · 2014-07-07 04:55:19Z

In your code, you are replacing any instance of the first letter "L" in the remainder of the string. In the case of the example, "Lulla", the first letter is a capital "L", and is not equal to "l". As such, I would try the following:

def fix_start(s):
    start_letter = s[0]
    rest_letters = s[1:]
    rest_letters = rest_letters.replace(start_letter.lower(),'*')
    return start_letter + rest_letters

The above solution will work if you have strings that are guaranteed to be syntactically correct (as in no uppercase letters in the middle of the word).

If that is not guaranteed, go ahead and try this:

def fix_start(s):
    start_letter = s[0]
    rest_letters = s[1:]
    rest_letters = rest_letters.replace(start_letter.lower(),'*')
    rest_letters = rest_letters.replace(start_letter, '*')
    return start_letter + rest_letters

sundar nataraj · Accepted Answer · 2014-07-07 05:01:25Z

0

Actually your trying to replace L but rest of the characters are small l.Try using regular expression that makes this task easy.

import re
def fix_start(s):
    start_letter = s[0]
    regex = s[0].lower()+"|"+s[0].upper()
    rest_letters = s[1:]
    rest_letters = re.sub(regex, "*", rest_letters) 
    return start_letter + rest_letters

print (fix_start ('Lulla'))

answered Jul 7, 2014 at 5:01

sundar nataraj

8,7102 gold badges36 silver badges48 bronze badges

Collectives™ on Stack Overflow

Unexpected output in python program

4 Answers 4

1 Comment

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related