sub xorswap {
    $_[0] ^= $_[1] ^= $_[0] ^= $_[1];
}
$str="XORing is FUN!";
print "($str)\n";
xorswap( substr($str,0,6), substr($str,-6) );
print "($str)\n";
xorswap( substr($str,0,6), substr($str,-6) );
print "($str)\n";
xorswap( substr($str,0,9), substr($str,-9) );
print "($str)\n";
xorswap( $str, $str );
print "($str)\n";
__END__
(XORing is FUN!)
(s FUN! iXORing)
(XORing is FUN!)
(!u'R y:u;ng is)
(              )