notepad++ convert \section{text} to # text - regex

Question

I have some tex files with \section{text} and \subsection{text}, etc. And I want to convert them to # text and ## text in markdown files using regular expressions in Notepad++. How can I achieve that?

Answer 1

Open the replace window with Ctrl + H. Check the radio button "Regular Expression" and search for:
\\section\{([^}]*)}
And replace with:
# \1
For subsections:
\\subsection\{([^}]*)}
## \1
What we're doing:
\\ is an escaped backslash matching the litteral backslash of your expression
{ needs to be escaped as well otherwise it would be recognized as quantifier, hence \{
([^}]*) is a group made of 0 or more characters that are NOT }
\1 is a reference to the first and only group of our regular expression

Answer 2

It can be done in a single pass:
Ctrl+H
Find what: \\(sub)?section{([^}]*)}
Replace with: (?1#)# $2
CHECK Wrap around
CHECK Regular expression
UNCHECK . matches newline
Replace all
Explanation:
\\ # a backslash, have to be escaped
(sub)? # group 1, literally "sub", optional
section{ # literally
([^}]*) # group 2, 0 or more any character that is not "}"
} # "}" character
Replacement:
(?1#) # conditional replace, if group 1 exists, print a "#"
# $2 # "#", a space and content of group 2
Screenshot (before):
Screenshot (after):