I want to comment out all environments say myenv in a tex-file. I can find them with the regexp:
\\begin{myenv}\(.\|\n\).*?\\end{myenv}
(instead of \n I had do type C-q C-j).
But what would be the correct regexp for replacing? How to reverse it, i.e. uncomment all environments myenv?
I think, for what you are doing, the comment by Tobias provides a superior solution. And this question gives quite a few options for commenting out chunks of code. That said, I'll assume this is an issue with using emacs, rather than latex.
Make your entire regex match a group \(regex\), then the regex to replace it will be similar to \\iffalse \1 \\fi.
An easier solution would be to write a keyboard macro that finds the begin\end environment commands and inserts the comment code there.
M-x re-search-forward RET
MY_REGEXP RET
followed by
M-x comment-dwim RET
;;;
comment-dwim is at M-;
After re-search-forward the region should be visible.
If not C-x C-x resp. M-xexchange-point-and-markRET
\excludecomment{myenv}in the document preamble. Your regexp is interesting in the aspect that you only allow one newline behind\\begin{myenv}and the backslash for the or-operator is missing. I would expect\\begin{myenv}\(.\|n\)*\\end{myenv}as regexp. – Tobias Mar 22 '16 at 11:59C-q C-jfor the newline characternin my last comment. You have already mentioned that in your question. – Tobias Mar 22 '16 at 12:09myenvenvironments and applyingcomment-regionto each match. Or applyuncomment-regionto undo it. You should be able to use the same regexp for both cases. (Sorry, don't have the time to flesh this out to a proper answer.) – Harald Hanche-Olsen Mar 22 '16 at 12:23