You give no example of a failing  $text string in your most recent post nor in the previous ones (Pull 3-digit and 4-digit numbers from string, Recognizing numbers and creating links and Matching text in a string), but the advice offered is the same: do a single substitution. File s_4_digits_1.pl:

use warnings;
use strict;

my $text = qq{foo 1234 \n 1234 bar \n1234\n 1 22 333 55555 666666};
print qq{[[$text]] \n};

my $digits_4 = qr{ \b \d{4} \b }xms;
$text =~ s{ ($digits_4) }
          {<a href="script.pl?do=view&unit=$1"><b>$1</b></a>}xmsg;
print qq{[[$text]] \n};
[download]

c:\@Work\Perl\monks\htmanning>perl s_4_digits_1.pl
[[foo 1234
 1234 bar
1234
 1 22 333 55555 666666]]
[[foo <a href="script.pl?do=view&unit=1234"><b>1234</b></a>
 <a href="script.pl?do=view&unit=1234"><b>1234</b></a> bar
<a href="script.pl?do=view&unit=1234"><b>1234</b></a>
 1 22 333 55555 666666]]
[download]

Thank you so much for this. It works! This still tags 4-digit numbers as part of a phone number, but that's okay. I'd love to hire you for several projects as I'm just a hack.

I posted this solution in your previous thread, but maybe I was late and you missed it. It does the job while skipping phone numbers. If you don't understand any of it, just ask.

#!/usr/bin/env perl
use 5.010; use strict; use warnings;

my $text = <<END;
Apt.302. 123-4567. 4021
207-555-1531 Apt. 987
END

$text = " $text "; # pad it so my regex will work if a number 
                   # appears at the beginning or end of line
$text =~ s|(       # start capturing in $1
            [^\d-] # any single character other than a digit or dash
           )       # end capture of $1
           (       # start capturing in $2
            \d\d\d # three digits in a row
            \d?    # zero or one digits (for a total of 3-4)
           )       # end capture of $2
           (       # start capture of $3
            [^\d-] # any single character other than a digit or dash
           )       # end capture of $3
         |$1<a href="\?unit=$2"><b>$2</b></a>$3|gx; # Replace captured
                                                    # sections with HT
+ML added 
$text = substr($text, 1,-1);  # trim off padding
say $text;
[download]

Aaron B.
Available for small or large Perl jobs and *nix system administration; see my home node.

You're very welcome. I'm not in the job market right now. Have you tried Perl Jobs?

Another alternative is this site, where you can often find copious help for free! As aaron_baugher has alluded, several approaches to the phone number exclusion problem have already been given in answers to your previous posts. To get the most out of this site, you must be willing to give useable input and output data in addition to clear descriptions of your problem and, one hopes, your efforts at a solution. I.e., you must help us to help you.

---

Give a man a fish:  <%-(-(-(-<

my @nums = qw/ 3 9 2 9 /;;
{
  my $re = join '|', map { "\Q$_\E" } @nums;
  my $str = 'and a 3  9 2 9 ';
  $str =~ s{($re)}{"$1"}g;
  print "$str\n";
}

{
  my $re = join '\s*', map { "\Q$_\E" } @nums;
  my $str = 'and a 3  9 2 9 ';
  $str =~ s{($re)}{"$1"}g;
  print "$str\n";
}

__END__
and a "3"  "9" "2" "9" 
and a "3  9 2 9"
[download]