regex - Notepad++ use both regular expressions and extended search

Question

I need to find all that do not precede the letter M;
Seems I can't do this:

[^M]

I can only do with extended search selected or [^M] with regular expressions selected; but not together.

Answer 1

You should instead use this regex:

R(?!M)

Explanation:

• R Any Unicode newline sequence.
• (?!M) Negative Lookahead: Assert "M" cannot be matched.