Python - How to carry out string operations?

Question

Code:

str="Hello World"         
for i in range(len(str)):                  
  str[i]=str[len(str)-i]    
print(str)

This corresponds to an error in Python. What would be the right way to implement this?

What is your expected output ? what do you want to achieve ? what is the error ? **What is the question?** — ZdaR, Jun 03 '15 at 04:17
possible duplicate of [Reverse a string in Python](http://stackoverflow.com/questions/931092/reverse-a-string-in-python) — sobolevn, Jun 03 '15 at 04:24

score 3 · Accepted Answer · answered Jun 03 '15 at 04:20

3

In Python, strings are immutable. You can't reassign individual characters.
str is not a good variable name because it masks the built-in function str().
It looks like you want to reverse the string:

string = "Hello World"
reversed_string = string[::-1]

answered Jun 03 '15 at 04:20

TigerhawkT3

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Thank you, but i actually wanted the mirror image of the string along its center. Can you help? – Sourav Jun 03 '15 at 04:33
1

Mirroring both ends along the center is equivalent to reversing it. If you want something else, please clarify the expected input and output. – TigerhawkT3 Jun 03 '15 at 04:36

score 1 · Answer 2 · answered Jun 03 '15 at 05:04

1

try to following:

string = "Hello World"
print string[::-1]
print ''.join(reversed(string))

answered Jun 03 '15 at 05:04

Haresh Shyara

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score 0 · Answer 3 · answered Jun 03 '15 at 09:49

In fact, I think the key problem of you is that you don't understand that string in python is immutable, yet you can read str[i] but this don't mean that you can change str[i],never do this: one_string = "..." one_string[i] = ".." remember one_string[i] is read only. You can just use some standard lib funcion to replace part of the string, but some thing like one_string[i] = "..." is absolutely wrong.

Python - How to carry out string operations?

3 Answers3