Coursera: Parts of a String

Question

I'm having a bit of trouble with a Python problem that involves strings.

The prompt is:

Modify the first_and_last function so that it returns True if the first letter of the string is the same as the last letter of the string, False if they’re different. Remember that you can access characters using message[0] or message[-1]. Be careful how you handle the empty string, which should return True since nothing is equal to nothing.

This is what I have:

def first_and_last(message):
  for char in message:
    if char[0] == char[-1]:
      return True
    elif char == " ":
      return True
    else:
      return False

print(first_and_last("else"))
print(first_and_last("tree"))
print(first_and_last(""))

And the output I'm receiving:

True
True
None

Not quite, first_and_last("tree") returned True, should be False. Have you added the check for empty strings, and used correct string indexing? Hint: what do the index numbers of 0 and -1 mean for string handling in Python?

Anyone have any idea how to help?

Hint: When indexing strings, the index numbers `0` and `-1` mean mean the first character and last character respectively of the string. — martineau, Mar 22 '20 at 00:04

score 1 · Answer 1 · answered Mar 21 '20 at 23:46

I'll avoid answering the problem itself and try to give some hints to guide you:

"What do the index numbers of 0 and -1 mean for string handling in Python?" - well, this was already given to you.
What is the difference between char and message? What types of objects are both of those? In fact, char[0] and char[-1] seems odd. Shouldn't that cause an exception?
Programming languages, especially ones like python, are a playground. Printing objects usually helps you understand what's going on. (Try printing each char in the message and see what you get)

score 1 · Answer 2 · edited Apr 09 '20 at 11:18

1

You can use the 'not' and 'or' comparison operators to output the desired result.

def first_and_last(message):
    if not message or message[0] == message[-1]:
        return True
    else:
        return False

edited Apr 09 '20 at 11:18

marc_s

732,580
175
1,330
1,459

answered Apr 01 '20 at 04:18

minTwin

1,181
2
21
35

1

Please add a few sentences to explain what your code is doing, so you can get more upvotes for your answer. – Fuzzy Analysis Apr 01 '20 at 07:19

score 0 · Answer 3 · edited May 01 '20 at 02:16

0

def first_and_last(message):
  if not message or message[0] == message[len(message)-1]:
    return True
  else:
    return False

edited May 01 '20 at 02:16

4b0

21,981
30
95
142

answered Apr 30 '20 at 21:46

Ashutosh kumar

1

Please add some explanation to your answers on stackoverflow – zoran404 Apr 30 '20 at 22:21
While this code may provide a solution to problem, it is highly recommended that you provide additional context regarding why and/or how this code answers the question. Code only answers typically become useless in the long-run because future viewers experiencing similar problems cannot understand the reasoning behind the solution. – E. Zeytinci May 01 '20 at 12:01

score 0 · Answer 4 · edited Jun 30 '20 at 17:39

0

def first_and_last(message):
    if len(message)==0:
        return True
    else:
        return message[0]==message[-1]

edited Jun 30 '20 at 17:39

slava-kohut

4,203
1
7
24

answered Jun 30 '20 at 10:06

Atharva Hire

1

Please, use ctr+k to show your codes in a code format. – Hamed Baziyad Jun 30 '20 at 10:22

score 0 · Answer 5 · answered Nov 10 '20 at 18:03

def first_and_last(message):
  if not message or message[0] == message[len(message)-1]:
    return True
  else:
    return False

print(first_and_last("else"))
print(first_and_last("tree"))
print(first_and_last(""))

Here is your output:
True
False
True

score 0 · Answer 6 · edited Jun 11 '22 at 00:37

0

def first_and_last(message):
    if len(message)==0 or message[-1]==message[0]:
        return True
    else:
        return False

print(first_and_last("else"))
print(first_and_last("tree"))
print(first_and_last(""))

Here is your output:

True
False
True

edited Jun 11 '22 at 00:37

S.B

13,077
10
22
49

answered Jun 08 '22 at 23:21

Konstantin Andreyev

27
4

score 0 · Answer 7 · answered Jul 13 '22 at 09:28

0

Hey I was getting the same issue with the problem when I was trying to solve it. Mainly I was getting issue for the null string. If you do not use or operation in your code try using the condition for null string first.

answered Jul 13 '22 at 09:28

Anu

13
4

This does not provide an answer to the question. Once you have sufficient [reputation](https://stackoverflow.com/help/whats-reputation) you will be able to [comment on any post](https://stackoverflow.com/help/privileges/comment); instead, [provide answers that don't require clarification from the asker](https://meta.stackexchange.com/questions/214173/why-do-i-need-50-reputation-to-comment-what-can-i-do-instead). - [From Review](/review/late-answers/32236366) – Rabinzel Jul 17 '22 at 06:15

Coursera: Parts of a String

7 Answers7