How to Modify Individual Characters in Immutable Python Strings?

Error: 'str' Object Does Not Support Item Assignment

Python strings are immutable, meaning that once created, their individual characters cannot be modified. Attempting to modify a character directly using item assignment, as in the code s2[j] = s1[i], results in the error "TypeError: 'str' object does not support item assignment."

This behavior is in contrast to languages like C, where strings are mutable and can be modified in this way. To overcome this limitation in Python, consider the following alternatives:

Using String Concatenation

Instead of directly assigning to individual characters, you can build a new string by concatenating the desired characters. For instance:

<code class="python">s1 = "Hello World"
s2 = ""
j = 0

for i in range(len(s1)):
    s2 += s1[i]</code>

Here, s2 is created by appending characters from s1 one at a time.

Converting to Lists

Python strings can be temporarily converted to lists, modified, and then converted back to strings. For example:

<code class="python">s1 = "Hello World"
list1 = list(s1)
list1[5] = 'u'
s1 = ''.join(list1)</code>

In this case, s1 is converted to a list list1, where the fifth character is modified. list1 is then converted back to a string s1 with the requested modification.

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