It doesn't work because there's no end token before the two single quotes.

I'm not sure there's a way to do this within a single, maintainable regular expression. I'd rather inch through the file, keeping a flag to signify whether or not I'm in an embedded code sequence, replacing all single quotes while I'm not.

I asked a similar question a while ago, and lots of fellow monks helped me at that time, and I learned a lot, (now their names are much more familiar to me than they did back then ;-)

Make some slight changes to some of those solutions, you will get what you want.

I don't want to steal their smart solutions, and make those look like mine, so I just give you the link to that thread, you can see those solutions and their authors.

i'm trying to write a regular expression that will replace all single quotes (') not contained in <%...%> tags with a separate string.

The recipe I've used for years now: match the skip sequence, or the string you want to match, in that order. If you found a skip sequence, replace the matched string by itself, otherwise, replace by whatever you want.

A conversion to simple code:

<s/(<%.*?%>)|(')/$1 || 'test'/seg;
[download]

#!/usr/bin/perl

use strict;
use warnings;

while (<DATA>) {
    s/(<%(?:[^%]+|%[^>])*%>)|'/$1 || ""/eg;
    print;
}


__DATA__
Leave this line alone.
Remove this quote ' and these two quotes '' from this line.
Leave <% the first quote ' %> alone, but remove the second ' one.
Remove from <% an open but not closed ' tag.
' Leading quote?
<% Multiple ' tags %> ' on one ' <% line ''' work  %> too ' !
[download]

Running this gives:

Leave this line alone.
Remove this quote  and these two quotes  from this line.
Leave <% the first quote ' %> alone, but remove the second  one.
Remove from <% an open but not closed  tag.
 Leading quote?
<% Multiple ' tags %>  on one  <% line ''' work  %> too  !
[download]

$_=<<ENDHERE;
"Avert thine eyes, lest ye be stricken with coolness." (from the origi
+nal batkins web site, dated April 8, 2002
 )<br><br>
 <a href="http://batkins.com/forum/YaBB.pl">Enter the batkins forum</a
+> - it's the place to be.
 <br><br>
 batkins.com is best viewed from the Hubble Telescope.
 <br><br>
 <hr>
 <font size="+1"><b><u>the batkins weblog - it's nature's candy</u></b
+></font>
 <br><br>
 <%
     # news
     my @news = split(/%%/, slurp("$DAT/news"));
     my $bit;
     my $i;
     for($i = 0; $i < 10; $i++)
     {
         $bit = "<b>$news[$i]</b><br>" . $news[$i + 1] . "<p>";
         print $bit;
         $i++;
     }

 %>
 <a href="/main/news.pl">View the rest of the weblog (<% print scalar(
+@news) - $i; %> more entries)</a>
 <p>
 <font face="-2"><a href="/main/all.pl">the batkins directory</a></fon
+t>
ENDHERE
s/'|(<%.*?%>)/$1||'test'/egs;
print;
[download]

s/
  (
    (?:        # non capturing parens
      ^|%>  # start of string or %>
    ) 
    .* 
  )
  '
  (.*
     (?:<%|$) 
  )
/$1 SOMESTRING $2/gsx # add s and x modifiers
[download]

thanks again.

-bill