PHP ob_flush问题

Question

Is ob_flush necessary and what does it do exactly? I ask because I have at the bottom of my footer and for some reason its not letting me destroy a session variable correctly.

code.

if(isset($_GET['a']) && is_numeric($_GET['a'])) {
    if(isset($_SESSION['page']) && $_SESSION['page'] !== $_GET['a']){
        unset($_SESSION['page']);
    }

    $page = mysqli_real_escape_string($mysqli, htmlentities(strip_tags($_GET['a'])));
    $_SESSION['page'] = $page;
}

Answer 1

if you've used ob_start, then ob_flush will output everything that would normally have been printed out since ob_start was called. Post some code for more detailed help.