use strict;
my $str = 'HIT & REPLACE
11/21/1994
12/11/2014
03/31/2016 # Hit only if unchecked for length months/days
NO-HIT
11//12/2090
37/14/2015
20/27/2011
10/32/1964
14/03/2020
HINTS
- Use g-flag only.
';
my $regex = qr/(.*)/mp;
my $subst = '$1,$1,$1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html