To summarize: the problem is in the pattern, (or in the fact that you didn't check if the pattern mached at all).

I've changed three things about the pattern:

  1. ? instead of {0,1}
  2. ^ just once
  3. \d+ instead of \d*
  4. discarded the /m at the end 
while (<DATA>) {

        chomp;
        print "Test case '$_'\n";

        if (  m!^(-?\d+)\s+(-?\d+)!  )
        {
                print "$_, " for ($1 .. $2);
        }
        else
        {
                print "doesn't match";
        }

        print "\n\n";

}

__DATA__
1 6
-4 6
-4 -1
6 1
6 -4
-1 -4

[download]

making the program count *backwards* is left as an exercise to the reader. 

--
Brigitte    'I never met a chocolate I didnt like'    Jellinek
http://www.horus.com/~bjelli/         http://perlwelt.horus.at

In reply to Re: regex negative numbers by bjelli
in thread regex negative numbers by Anonymous Monk

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