CODEWITHSUNDEEP
python-3.x
Kasturi Karuna
Kasturi Karuna

Reputation: 1

Confused on the function of "r"(raw string characters)

Confused over the purpose of "r". As i understand it helps to read as a normal character than its usage as an escape character

I tried multiple codes as follows and all are giving the same output. This is making me confused on the real interpretation of "r". While i agree with first 3 lines of code.Fourth one is where im confused.

1.re.sub("n\'t", " not", " i am n't happy")
2.re.sub("n\'t", " not", " i am n\'t happy")
3.re.sub(r"n\'t", " not", " i am n\'t happy")
4.re.sub(r"n\'t", " not", " i am n't happy")

Result of all 4 above is :'

' i am not happy'

import re

re.sub(r"n\'t", " not", " i am n't happy")

Given that i have used "r" i expected the backslash to be treated as a characters and not escape character

Actual Output ' i am not happy'

Expected Output ' i am n't happy'

Upvotes: 0

Views: 74

Answers (1)

RemcoGerlich
RemcoGerlich

Reputation: 31260

The thing is that there are two layers of -escaping: in the string literal, and in the regex. And in neither does \' have a special meaning, and it's just treated as '.

What using r"" does here is to skip the first string-literal escaping, so that a literal \ is included in the string, but then the regex sees the string \' and just treats it as '.

So all four come down to replacing n't with not.

You still need double backslashes to match a literal backslash.

Upvotes: 1

Related Questions