how to expire php session if user is inactive for 15 mins

Question

i have created one project in PHP, into which i am managing sessions.

I am creating session in my config.php file by writing following line of code.

session_start();

and to destroy this session, in logout.php file i have write following line.

session_destroy();

and i have not mention any code for session in any other project file, but the problem is session is active untill i call logout.php,

what i want is session should expire if user is inactive for 15 minutes.

can anyone help me for this, i am new to PHP, please give some example code or link to achieve this..

Answer 1

Call below function in your header file, so that whenever user does any activity at that time page gets refreshed and check whether session time outs or not.

function auto_logout($field)
{
    $t = time();
    $t0 = $_SESSION[$field];
    $diff = $t - $t0;
    if ($diff > 1500 || !isset($t0))
    {          
        return true;
    }
    else
    {
        $_SESSION[$field] = time();
    }
}

Use something like this in header

    if(auto_logout("user_time"))
    {
        session_unset();
        session_destroy();
        location("login.php");          
        exit;
    }       

User_time is the session name. I hope this answer will help you. What actually this code does is : "Checks whether diff is greater than 1500 seconds or not. If not then set new session time." You can change time diff(1500) according to your requirement.