Slicing to reverse a string does not work in this case

Question

I am a new bee in python. Trying to reverse the string using slicing. It does not work? why?

ex='The Man'
reverse = ex[6:-1:-1]

Possible duplicate of [Reverse string Python slice notation](https://stackoverflow.com/questions/40253256/reverse-string-python-slice-notation) — Arkistarvh Kltzuonstev, Jul 14 '19 at 09:54

score 3 · Answer 1 · answered Jul 14 '19 at 09:52

3

Just do:

ex='The Man'
reverse = ex[::-1]

answered Jul 14 '19 at 09:52

U13-Forward

Vinay Hegde · Answer 2 · 2019-07-14T10:01:24.987

1

Try this :

str='The Man' 
stringlength=len(str)
slicedString=str[stringlength::-1] 
print (slicedString)

edited Jul 14 '19 at 10:01

answered Jul 14 '19 at 09:54

Vinay Hegde

It's not a good practice to use a data type as a variable name like `str`. Kindly check the edit suggestion. Moreover, the start index in your case is `len(str)`, which, however, doesn't exist. It should be `len(str) - 1`. – Achint Sharma Jul 14 '19 at 10:39
Yes. It would work but you iterating one extra time. Checkout this: https://onlinegdb.com/BkRy-c_br – Achint Sharma Jul 14 '19 at 11:25

score 1 · Answer 3 · answered Jul 14 '19 at 09:54

1

This is because start index and end index are the same, i.e., 6 and -1 are one and the same index. You should try:

ex='The Man'
reverse = ex[6::-1]

answered Jul 14 '19 at 09:54

Achint Sharma

How? Is the string saved in circular array – Randy Jul 14 '19 at 10:04
You have hard coded the index. What if `ex` value is something like this `stack overflow` ? . Will you do `reverse=ex[13::-1]` ? . Not a good idea though!. – Vinay Hegde Jul 14 '19 at 10:10
@VinayHegde This answer was for this specific case. For a generic case, your answer will prove to be a better approach. – Achint Sharma Jul 14 '19 at 10:32
@Randy No. The negative index `i` is equivalent to the index `length of string - absolute value of i `, i.e. in your case `-1` is equivalent to `7 - 1` , i.e. `6`. That's how a negative index is defined. Also here, `ex[6::-1]` means: Start from index 6, decrement `1` at a time up to `0`. – Achint Sharma Jul 14 '19 at 10:42

Ryuzaki L · Answer 4 · 2019-07-14T10:09:52.910

1

This

ex='The Man'
reverse = ex[::-1]

or

ex='The Man'
reverse = ex[-1:-8:-1]

edited Jul 14 '19 at 10:09

answered Jul 14 '19 at 09:56

Ryuzaki L

How? Why that -1 and -8 – Randy Jul 14 '19 at 10:05
start index is `-1`, and end index is `-8` of string to be reversed @Randy – Ryuzaki L Jul 14 '19 at 10:09

score 1 · Answer 5 · answered Jul 14 '19 at 10:32

1

ex='The Man'
reverse = ex[-1::-1]

The index can start from 0 to len(ex)-1 or -len(ex) to -1. other index will cause out of range.

answered Jul 14 '19 at 10:32

5 Answers5