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], it gives an ERROR:

s2[j] = s1[i] 

# TypeError: 'str' object does not support item assignment

In C, this works:
 

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

My attempt in Python is :

s1 = "Hello World" 
s2 = "" 
j = 0 

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

Answer 1

In Python, strings are not very mutable which states that you cannot 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, following which it stores the reference to that new string in s2. Options are always open and you can use something like:
 

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

Hope this answers your question!!