Now I think I should say that I am not aware of any compiler that will compile code with nested comments, so this is probably not a big problem.

However I played around and this seems to do the trick: (just replace the while loop in my code above with this one.) 
while( $file =~ /\Q$start\E(.*?)\Q$end\E/sg )
{
    $a = $1;
    $match = $&;
    
    #look for more start tags in what we matched 
    while( $a =~ /\Q$start\E/sg )
    {
        #balance the ending comments
    $file =~ /.*?\Q$end\E/sg;    
        $match .= $&;
    }
    print $match, "\n";
}

[download]
For your tests file I got what you wanted.

For other tests I used this test.txt: 
blah blah
/* comment 1 */

blah blah
/* comment 2 */
blah blah
/*  outer 
    /* 
        mid
            /*
                center
            */
        mid  
    */ 
    outer 
*/

[download]
And here are my results: 
prompt$ regex.pl '/*' '*/'
/* comment 1 */
/* comment 2 */
/*  outer
    /*
        mid
            /*
                center
            */
        mid
    */
    outer
*/

[download]
So enjoy this fanciful result.

I hope this helps.

In reply to Re: matching comments by perlmonkey
in thread matching comments by Eugene

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.