'str' object does not support item assignment

Question

I would like to read some characters from a string s1 and put it into another string s2.

However, assigning to s2[j] gives an error:

s2[j] = s1[i]  # TypeError: 'str' object does not support item assignment 

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In C, this works:

int i = j = 0; while (s1[i] != '\0')     s2[j++] = s1[i++]; 

My attempt in Python:

s1 = "Hello World" s2 = "" j = 0  for i in range(len(s1)):     s2[j] = s1[i]     j = j + 1 

Answer 1

The other answers are correct, but you can, of course, do something like:

>>> str1 = "mystring" >>> list1 = list(str1) >>> list1[5] = 'u' >>> str1 = ''.join(list1) >>> print(str1) mystrung >>> type(str1) <type 'str'> 

if you really want to.

Answer 2

In Python, strings are immutable, so you can't change their characters in-place.

You can, however, do the following:

for c in s1:     s2 += c 

The reasons this works is that it's a shortcut for:

for c in s1:     s2 = s2 + c 

The above creates a new string with each iteration, and stores the reference to that new string in s2.