session_destroy() after certain amount of time in PHP - php

Question

I am currently saving a session in my form page:
$testingvalue = "SESSION TEST";
$_SESSION['testing'] = $testingvalue;
On another page I am calling the session to use the value:
<?php
session_start(); // make sure there is a session
echo $_SESSION['testing']; //prints SESSION TEST???
?>
Now I want to use the
session_destroy();
to destroy the session. But what I would like to do is destroy the session after 2 hours have been passed.
Any idea on how to do it and also where should I put it?
I have something like this:
<?php
session_start();
// 2 hours in seconds
$inactive = 7200;
$session_life = time() - $_session['testing'];
if($session_life > $inactive)
{
session_destroy();
}
$_session['testing']=time();
echo $_SESSION['testing']; //prints NOTHING?
?>
Will that work?
If I am inactive for more than 2 hours this should be blank?:
echo $_SESSION['testing'];

Answer 1

Something like this should work
<?php
// 2 hours in seconds
$inactive = 7200;
ini_set('session.gc_maxlifetime', $inactive); // set the session max lifetime to 2 hours
session_start();
if (isset($_SESSION['testing']) && (time() - $_SESSION['testing'] > $inactive)) {
// last request was more than 2 hours ago
session_unset(); // unset $_SESSION variable for this page
session_destroy(); // destroy session data
}
$_SESSION['testing'] = time(); // Update session

Answer 2

you need a static start time to expire. $session_life > $inactive will always be greater no matter what.
session_start();
$testingvalue = "SESSION TEST";
$_SESSION['testing'] = $testingvalue;
// 2 hours in seconds
$inactive = 7200;
$_SESSION['expire'] = time() + $inactive; // static expire
if(time() > $_SESSION['expire'])
{
$_SESSION['testing'] = '';
session_unset();
session_destroy();
$_SESSION['testing'] = '2 hours expired'; // test message
}
echo $_SESSION['testing'];
or session-set-cookie-params