PHP301跳转不带www域名的网址

//如果域名是不带www的网址那么进行下面的301跳转
$the_host = $_SERVER[‘HTTP_HOST’];
$th{e}_{u}rl=isset($_SERVER[‘REQUEST_URI’]) ? ${}_{S}ERVER{[}^{\prime }REQUES{T}_{U}R{I}^{\prime }]{:}^{\prime \prime };if(strpos($the_host,‘www.’)===false)
{
header(‘HTTP/1.1 301 Moved Permanently’);
header(‘Location:http://www.’.$th{e}_{h}ost.$the_url);
exit();
}