Re: regex: something...(!something)...something

[Roy Johnson]

My tutorial on look-ahead and look-behind covers this. You're specifying that the open tag is not followed immediately by another open tag; you want to specify that it's followed by any arbitrary text that isn't an open tag. This s/// expression should do what you want:

$x =~ s{(?<=<td>)((?:(?!<td>).)*)3((?:(?!</td>).)*)(?=</td>)}{$1a$2};

Update: I should have broken this down in commented style (I also note that I could have done lookahead for everything after the 3):

$x =~ s{(?<=<td>)         # Start match with open-tag
        (                 # Capture
          (?:(?!<td>).)*  #  Any number of characters that do not star
+t an open-tag
        )3                # Close capture; match literal 3
        (?=               # Look ahead to match
          (?:(?!</td>).)* #  Any number of characters that do not star
+t a close-tag
         </td>            #  then a close-tag
        )}                # End lookahead and pattern
       {$1a}x;

[aaaone]

Thank you! It also works (I see it is more complex then Oluses regex, but probably more universal). I'll read your tutorial and will try to never ask again stupid questions about regexes :)