Why are Python strings immutable? What does befits of it?

Question

I'm trying to search for several strings, which I have in a .txt file line by line, on another file. So the idea is, take input.txt and search for each line in that file in another file, let's call it rules.txt.

So far, I've been able to do this, to search for individual strings:

import re
shakes = open("output.csv", "r")

for line in shakes:
 if re.match("STRING", line):
 print line,

How can I change this to input the strings to be searched from another file?

Answer 1

Python String are immutable. There is some advantage to have string as immutable.

First advantage is performance, knowing that a string is immutable means we can allocate space for it at creation time, and the storage requirements are fixed and unchanging. This is also one of the reasons for the distinction between tuples and lists.

Another advantage is that strings in Python are considered as "elemental" as numbers. No amount of activity will change the value 8 to anything else, and in Python, no amount of activity will change the string "eight" to anything else.