簡單靈活的 PHP頁面跳轉函數

<?
        function Location($url =  null){        
                $location =  null;
                 if ( !$url) {
                        $url =  $_SERVER[ ' PHP_SELF '];
                }
                elseif ( substr($url, 0, 1) ==  ' ? ' ) {
                        $url = $_SERVER[ ' PHP_SELF '] . $url;
                }
                 if ( substr($url, 0, 7) ===  ' http:// ' or substr($url, 0, 8) ===  ' https:// ' ) {
                        $location = $url;
                }
                 else {
                        $port =  null;
                         if ( $_SERVER[ ' SERVER_PORT '] ==  443 ) {
                                $protocol =  ' https:// ';
                        }        
                         else {
                                $protocol =  ' http:// ';
                                $checkPoint=explode( " : ",$_SERVER[ ' HTTP_HOST ']);
                                  if (count($checkPoint)== 0) {
                                         $port =  ' : '.$_SERVER[ ' SERVER_PORT '];        
                                 }                                
                        }
                        $dir = dirname($_SERVER[ ' SCRIPT_NAME ']);
                         if ( $dir ===  " / " ) {
                                $dir =  "";
                        }
                         if ( substr($url, 0, 2) ===  ' ./ ' ) {
                                 if ( $dir ) {
                                        $location = $protocol . $_SERVER[ ' HTTP_HOST '] . $port .  ' / ' . $dir        .  ' / ' . basename($url);
                                }
                                 else {
                                        $location = $protocol . $_SERVER[ ' HTTP_HOST '] . $port .  ' / ' . basename($url);
                                }
                        }
                        elseif ( substr($url, 0, 1) ===  " / " ) {
                                $location = $protocol . $_SERVER[ ' HTTP_HOST '] . $port . $url;
                        }
                         else {
                                $location = $protocol . $_SERVER[ ' HTTP_HOST '] . $port . $dir .  ' / ' . $url;
                        }
                }
                header( " Location: $location ");
                exit();

        }

?>

 
          // 
           跳轉到百度首頁  
          
Location( 
          ' 
          http://www.baidu.com 
          ');