while ($string =~ /($regex)/pg){
 my $match = ${^MATCH};
 my $start = $-[0];
 my $end = $+[0];
 my $hitpos = "$start-$end";
 my $lcmatch = lc($match);
 $string =~ s/$match/$lcmatch/g;
 push @matches, "$match found at $hitpos ";
 }