So how will it know it's me? Most sessions set a cookie on your computer to uses as a key... it will look something like this: 350401be75bbb0fafd3d912a1a1d5e54. Then when a session is opened on another page, it scans your computer for a key. If there is a match, it accesses that session, if not it starts a new session for you.

Part 2 - Using Session Variables

Now we are going to make a second page. We again will start with session_start() (we need this on every page) - and we will access the session information we set on our first page. Notice we aren't passing any variables, they are all stored in the session.

Call this code mypage2.php

    // this starts the session
    session_start();

    // echo variable from the session, we set this on our other page
    echo "Our color value is ".$_SESSION['color'];
    echo "Our size value is ".$_SESSION['size'];
    echo "Our shape value is ".$_SESSION['shape'];

All of the values are stored in the $_SESSION array, which we access here. Another way to show this is to simply run this code:

    session_start();
    Print_r ($_SESSION);

You can also store an array within the session array. Let's go back to our mypage.php file and edit it slightly to do this:

    session_start();

    // makes an array
    $colors=array('red', 'yellow', 'blue');
    // adds it to our session
    $_SESSION['color']=$colors;
    $_SESSION['size']='small';
    $_SESSION['shape']='round';
    print "Done";

Now let's run this on mypage2.php to show our new information:

    session_start();
    Print_r ($_SESSION);
    echo "

";

    //echo a single entry from the array
    echo $_SESSION['color'][2];

Part 3 - Modify or Remove Session

    // you have to open the session to be able to modify or remove it
    session_start();

    // to change a variable, just overwrite it
    $_SESSION['size']='large';

    //you can remove a single variable in the session
    unset($_SESSION['shape']);

    // or this would remove all the variables in the session, but not the session itself
    session_unset();

    // this would destroy the session variables
    session_destroy();

The code above demonstrates how to edit or remove individual session variables, or the entire session. To change a session variable we just reset it to something else. We can use unset() to remove a single variable, or session_unset() to remove all variables for a session. We can also use session_destroy() to destroy the session completely.

By default a session lasts until the user closes their browser. This can be changed in the php.ini file by change the 0 in session.cookie_lifetime = 0 to be the number of seconds you want the session to last, or by using session_set_cookie_params().