Perl中的向后引用

\n表示向后引用

use strict;
use warnings;
my $str = "<title> hello world </title>";


if($str =~ /(?#start of a tag)<([^>]+)>(.*?)(?#end od a tag)<\/(\1)>/){
	print "$1\n";
	print "$2\n";
	print "$3\n";
}