如果用户已登录，则更改index.php的内容，而无需创建另一个页面

<?php
    // ASSUMING YOU HAVE A CLASS THAT PRE-BUILDS HTML-MARKUP FOR EACH PAGE
    // THE CLASS MAY LOOK SOMETHING LIKE THIS:
    class MarkUpHelper{
        public static function getHomePage(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Home-Page...
                    May require Database Access but here,
                    the HTML is generated & returned.";
        }
        public static function getCustomizedUserPage($userID){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Customized User-Page...
                    May require Database Access using the $userID but here,
                    the HTML is generated & returned.";
        }
        public static function getLoginPage(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Login Page...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
        public static function getRegistrationPage(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Registration Page...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
        public static function getSideBarLeft(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Side-Bar Left Component(s)...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
        public static function getSideBarRight(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Side-Bar Right Component(s)...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
        public static function getFooter(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Footer Component(s)...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
        public static function getHeader(){
            // YOU MAY EVEN LOAD/REQUIRE STATIC FILES: HTML, TXT, ETC
            // AND PARSE THE CONTENT TO A STRING (HTML-STRING)
            // AND THEN RETURN THE STRING VALUE
            return "HTML Markup for Header Component(s)...
                    May require Database Access ...here...
                    the HTML is generated & returned.";
        }
    }
?>

现在在index.php中，您可以这样做:

<?php
    // AUTOLOAD OR MANUALLY INCLUDE THE MarkUpHelper CLASS
    // CHECK IF USER IS LOGGED IN, THEN BUILD THE CUSTOM USER-PAGE.
    // IF NOT,SIMPLY SHOW THE HOME-PAGE...
    // THE VARIABLE: $userIsLoggedIn ASSUMES THERE IS A WAY TO GET THIS.
    // THE VARIABLE: $userID ASSUMES THERE IS A WAY TO OBTAIN THIS VALUE: PERHAPS FROM $_SESSION
    if($userIsLoggedIn){
        $output = MarkUpHelper::getCustomizedUserPage($userID);
    }else{
        $output = MarkUpHelper::getHomePage();
    }
    echo $output;