Change letters in a string in Python

Question

I'm figuring out some basics in python, and somehow I don't get things to work.

string = 'water'

string.replace('a','u')

print(string)

I want this script to print out wuter. Yet even with the string.replace it still prints out water. What am I doing wrong?

replace() is an inbuilt function in Python programming language that returns a copy of the string — thibsc, Aug 26 '20 at 21:27
Just to complement what previous comments said, I would recommend reading this old but helpful SO question which clarifies what does immutable means: https://stackoverflow.com/questions/9097994/arent-python-strings-immutable-then-why-does-a-b-work — KingDarBoja, Aug 26 '20 at 21:31
Also type `help(string.replace)` and it tells you "Return a copy of S with all occurrences of substring old replaced by new." — alani, Aug 26 '20 at 21:40

score 2 · Answer 1 · answered Aug 26 '20 at 21:28

2

string.replace('a','u')

doesn't change string. It returns a new string (which you discard in your case). Try

string = string.replace('a','u')

instead.

answered Aug 26 '20 at 21:28

adjan

Seyi Daniel · Answer 2 · 2020-08-26T21:30:35.657

0

You can get it done using Regex module substitute

import re
my_string = 'water'
my_string2 = re.sub('a', 'u', my_string)
print(my_string2)

edited Aug 26 '20 at 21:30

answered Aug 26 '20 at 21:29

Seyi Daniel

1

Really no need to use `re` module in this case – thibsc Aug 26 '20 at 21:29
Does it really change anything? – Seyi Daniel Aug 26 '20 at 21:34
In term of result, no. But I think it's a bad idea to answer with a regex in a case where it is not a good regex case. Because regex can be a performance issue. So short answer: No, long answer in this case: Yes – thibsc Aug 26 '20 at 21:38

2 Answers2