How to write regular expression that covers small and capital letters of a specific word?-CodePudding

I am trying to use regular expression to find a specific word (with small or capital letters) in a text.

Examples are:

none
None
NONE

However, the following code doesn't find the pattern in sample texts.

import re

txt_list = ["None" , "none", "[none]", "(NONE", "Hi"]
pattern = "/\bnone\b/i"


for txt in txt_list:
    if re.search(pattern, txt):
        print(f'Found {txt}')

What is the cause of the above issue? Is the "pattern" incorrect?

CodePudding user response：

Do not use slashes to delimit the regular expression. The syntax in Python is different. You can use (?i) to ignore case. (Additionally, escape the backslashes or use raw strings.)

pattern = "(?i)\\bnone\\b"

You can also pass the re.IGNORECASE flag to re.search.

pattern = r"\bnone\b"
for txt in txt_list:
    if re.search(pattern, txt, re.IGNORECASE):
        print(f'Found {txt}')