[/wp_active.php]

if (!is_multisite ()) {Wp_redirect (Site_url ('/wp-login.php?action=register '));//redirect the user to a pre-made absolute URI

Die (); }
$WP _query->is_404 = false; $WP _query is a wp_query entity object defined in the wp-blog-header.php file that provides information about the current request. This symbol accesses the properties and methods of the class instance;

Is_multisite () function source code, is the WordPress own definition of a function
function Is_multisite () {if (defined (' multisite ')) return multisite;if (defined (' Subdomain_install ') | | defined (' VH OST ') | | Defined (' SUNRISE ')) return True;return false;}


Function Source code:

Wp_redirect(302) { 

Global$is _iis;/** * Filter the redirect location. * *@since 2.1.0 * *@param string $location the path to redirect. *@param int $status Status code to use. */$location = Apply_filters (' Wp_redirect ',$location,$status);/** * Filter the redirect status code. * *@since 2.3.0 * *@param int $status Status code to use. *@param string $location the path to redirect. */$status = Apply_filters (' Wp_redirect_status ', $status, $location);  if (! $location) return false;  $location = Wp_sanitize_redirect ($location);  if (!  $is _iis && php_sapi_name ()! = ' cgi-fcgi ') Status_header ($status); //This causes problems on IIS and some FastCGI setupsheader ("Location: $location", true, $status); 
                                           
                                            return 
                                            true;} 
                                                           

　　

　　

[/wp_active.php]