Suppose you have this file:
x
a
b
c
x
x
a
b
c
x
x
and you want to find the sequence abc (and select the whole 3 lines) with Notepad++ . How to express the newline in regex, please?
Notepad++ can do that comfortably, you don't even need regexes
In the find dialogue box look in the bottom left and switch your search mode to Extended which allows \n etc.
As odds on you're working on a file in windows format you'll be looking for \r\n (carriage return, newline)
a\r\nb\r\nc
Will find the pattern over three lines