#!/usr/bin/perl -T
use 5.016;

my $regex =  qr/^.*$/;     # match anything, including an empty string

my @strings = ('delete everything',
               'overclock till cpu smokes',
               'we ownz you exec(nasty code here)',
			   ' ',
			   '',
              );

untaint(@strings);

sub untaint() {
	
	for my $elem(@strings) {
		if ( $elem =~ /$regex/ ) {
			say "Thank you, sucker. You are borked, really bad!";
		}else{
			say "Oh look, untainting did something more than merely allow any-old-badstruff to pass untaint. string untainted was -|$elem|-";
		}
	}
}
##</code><code>##

C:\>untaint-bad.pl
Thank you, sucker. You are borked, really bad!
         |delete everything|' passed.
Thank you, sucker. You are borked, really bad!
         |overclock till cpu smokes|' passed.
Thank you, sucker. You are borked, really bad!
         |we ownz you exec(nasty code here)|' passed.
Thank you, sucker. You are borked, really bad!
         | |' passed.
Thank you, sucker. You are borked, really bad!
         ||' passed.