Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!oliveb!mipos3!omepd!merlyn
From: merlyn@iwarp.intel.com (Randal Schwartz)
Newsgroups: comp.lang.c
Subject: Re: regex for C comments
Message-ID: <4626@omepd.UUCP>
Date: 10 Jul 89 19:03:09 GMT
References: <19365@paris.ics.uci.edu>
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Reply-To: merlyn@iwarp.intel.com (Randal Schwartz)
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Organization: Stonehenge; netaccess via Intel, Hillsboro, Oregon, USA
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In-reply-to: schmidt@zola.ics.uci.edu (Doug Schmidt)

In article <19365@paris.ics.uci.edu>, schmidt@zola (Doug Schmidt) writes:
| In their book ``Introduction to Compiler Construction with UNIX,''
| Schreiner and Friedman provide the following LEX regular expression
| for recognizing C comments:
| 
| ----------------------------------------
| "/*""/"*([^*/]|[^*]"/"|"*"[^/])*"*"*"*/"
| ----------------------------------------
| 
| Ignoring the possibility of overflowing an internal LEX buffer,
| does anyone know of any legal C comments that fail to match
| with this regular expression?

Try:
  /***/

(This one was easy. :-)
The problem with this one is that
  "star" "not-slash"
can match
  "star" "star"
where the second star is sometimes the first star of the terminating
  "star" "slash"

This is a common problem with these regex's.  Now come on people,
is this one of those "20 most commonly asked questions in comp.lang.c"?

And who has the right answer?  (Not me.... I screwed up last time... :-)

Just another C hacker,
-- 
/== Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ====\
| on contract to Intel, Hillsboro, Oregon, USA                           |
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