how to find '/N/ ' using regexp

Question

I don't want to learn regexps only for this particular problem. I need to find some '/*N*/ ' comments through C++ files. Can someone write a regexp which finds such comments?

Are you literally looking for N, or is N the actual comment text? — onaclov2000, Oct 14 '10 at 14:09
`\/\*N\*\/` - and don't tag the question with `c++` if it is actually a `regex` problem... — eumiro, Oct 14 '10 at 14:10
possible duplicate of [Python snippet to remove C and C++ comments](http://stackoverflow.com/questions/241327/python-snippet-to-remove-c-and-c-comments) — kennytm, Oct 14 '10 at 14:10
@KennyTM -1: yes, everyone has python installed and already knows what a hell scripts are — , Oct 14 '10 at 18:06

score 2 · Accepted Answer · edited May 23 '17 at 09:58

2

Try this regex :

/\/\*(.*?)\*\//

This is how it works :

\/    <- The / character (escaped because I used / as a delimiter)
\*    <- The * character (escaped because it's a special character)
(     <- Start of a group
  .     <- Any character
  *     <- Repeated but not mandatory
  ?     <- Lazy matching
)     <- End of the group
\*    <- The * character
\/    <- The / character

Edit : It doesn't handle \n nor \r\n, if you want it to then consider @Alex answer with the m flag.

edited May 23 '17 at 09:58

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answered Oct 14 '10 at 14:08

Colin Hebert

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+1 (although I considered downvoting: The OP doesn't want to learn Regexps :-P ) – Boldewyn Oct 14 '10 at 14:12
I didn't say I don't want an explanation :D – Oct 14 '10 at 18:04

alex · Answer 2 · 2010-10-14T14:16:30.047

What about

/\/\*(.+?)\*\//m

$1 will be your comments.

Hopefully m pattern modifier will make the period (match all) match new lines (\n) as well.

Note the + means it will only match comments with at least one character - since it seems you want to know the comments themselves, this is OK (what use will 0 length comment be)?

However, if you want to know the total comment blocks, change the + (1 or more) to * (0 or more).

Also, why not give regex a try? It is tricky at the start because the syntax looks funny, but they are really powerful.

score 0 · Answer 3 · answered Oct 14 '10 at 14:08

0

How about: (?<=\/*)(.*?)(?=*\/)

Which uses lookbehinds and lookaheads and captures the comment text (otherwise remove the parens around the .*, not to capture). Make sure you use a multi-line search, because these are multi-line comments

answered Oct 14 '10 at 14:08

Michael Goldshteyn

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how to find '/*N*/ ' using regexp

3 Answers3

how to find '/N/ ' using regexp