t.php

<?php

    function setSessionTime($expire = 0)
    {
      if ($expire == 0) 
      { $expire = ini_get('session.gc_maxlifetime');}
      else
      {ini_set('session.gc_maxlifetime', $expire);}
        
      setcookie(session_name(), session_id(), time() + $expire);
    }

    session_start();
    setSessionTime(5); //必須放置在session_start()之後
    $_SESSION["username"] = "zwcwu";
?>
<h1> has init scession ! click t2.php to show result </h1>
 

t2.php

<?php
	 function setSessionTime($expire = 0)
    {
      if ($expire == 0) 
      { $expire = ini_get('session.gc_maxlifetime');}
      else
      {ini_set('session.gc_maxlifetime', $expire);}
        
      setcookie(session_name(), session_id(), time() + $expire);
    }

    session_start();
    if(empty($_SESSION["username"]))
    {
    	echo "session is null, please relogin now, login!!!!";
    }
    else{
    	setSessionTime(5);
    	echo "Your session value is :" . $_SESSION["username"];
    }

?>