Question

A very popular question is how to reverse a C-Style string. The C-Style string by definition is a string that is terminated by a null(‘\0’). Using C(or maybe C++), it is possible to use pointers to manipulate the string to reverse its contents in-place.

If somebody asks the question, “How do you reverse a C-style string in Python?”, what would some of the possible answers be?

Thanks

Answer 1

If you need to “reverse a C-style string in Python”, I think the end result must also be a c-style string.

That is how I would understand the question, but the above answers do not support this.

See the interactive session below:

>>> 
>>> original = "abc\0"
>>> finish_correct = "cba\0"
>>> original
'abc\x00'
>>> finish_correct
'cba\x00'
>>> 
>>> answer = original[:-1]  # remove final null
>>> answer = answer[::-1]  # reverse string
>>> # Extended slice syntax:  [begin:end:step]
>>> # So, [::-1] means take whole string, but in reverse.
>>> answer
'cba'
>>> answer = answer + "\0"
>>> answer
'cba\x00'
>>> answer == finish_correct
True

Also note, Python strings are immutable. This means that they can never be changed. You can make new strings that are assigned to the same variable name, but the in-memory image for a given strings will never change. Thus, the notion of “reverse a string in place” can not happen in Python.

Hope this helps. If so, please up-vote and accept the answer. Thanks. 🙂