rizalp/PHP: Session & Cookie

## PHP: Session & Cookie
<?php
//in the beginning. Before any html
session_start(); //always start before anything else
$_SESSION['username'] == 'John';

//on another page:
session_start();
if ( !isset($_SESSION['username'])) {
    header('Location: login.php');
    die();
}

echo $_SESSION['username'];
session_destroy();
print_r($_SESSION); //session information are still stored in $_SESSION
$_SESSION = array(); //remove it
?>

<?php //admin.php
    include 'functions.php';
    session_start();
    if (is_logged_in()) {
         header('Location: login.php');
         die();
    }
?>

<?php //functions.php
function is_logged_in(){
     return ( isset($_SESSION['username'] );
}
?>

<?php
//Cookies: max 4KB. Store more casual information. Like preferences
setcookie('fontSize', 25, time() + 60 * 30, '/', 'ulingame.com');
//in seconds. half an hour into future

//to delete, set the cookie into the past
setcookie('fontSize', 25, time() - 60 * 30);

//set the cookie as array. easier to manage
setcookie('prefs[fontSize]', 25);
setcookie('prefs[favoriteCategory]', 'news');
setcookie('prefs[screenWidth]', 1024);

echo $_COOKIE['fontSize']; //only after second request

if (isset($_COOKIE['prefs'])) { // you can't blindly assume cookies is availlable
        foreach($_COOKIE['prefs'] as $key => $val) {
        echo htmlspecialchars($key) . htmlspecialchars($val);
    }
}