$string =~ s/\</\&lt\;/g; 
$string =~ s/\>/\&gt\;/g; 
$string =~ s/[\"\'\}\{\)\(\+]//g; 
$string =~ s/<!(?:--[\s\S]*?--\s*)?>\s*//g; 
$string =~ s/[\~\^]//g; 
$string =~ s/~!/ ~!/g; 
$string =~ s/<*(javascript)[^>]+>//gi; 
$string =~ s/(<[\s\/]*)(script\b[^>]*>)/$1x$2/gi; 
$string =~ s/<*(iframe)[^>]+>//gi; 
$string =~ s/<*(script)[^>]+>//gi;

##</code><code>##

use CGI 
$q = new CGI;
$string = $q->param('string');