how to avoid multiple start session

[blackhorse]

1)

if(session_id() == "")
{
session_start();
}

2)

<?php
function start_session(){
static $started=false;
if(!$started){
session_start();
$started = true;
}
}
?>

3)

if (!isset ($_SESSION)) session_start();

These are three samples to avoid start session multiple times. It seems to me that the approach 3) is the best.

I would use approach 3), any advices on this issue? Will approach 1) or 2 be the best to use?

Thanks!

[Kudose]

//sessions.php
if(!defined(SESSIONS)){
 session_start();
 define('SESSIONS', TRUE);
}

//index.php
require_once('sessions.php');
echo 'Hi';
//include does nothing
include('sessions.php');

[blackhorse]

why not use this?

if (!isset ($_SESSION)) session_start();

or

if(session_id() == "") session_start();

This will cover all the multiple session_start(). This is simple enough. I can mass replace all the old scripts session_start() with the above codes and solve the problem.

Or the above two codes have some problems?

[NuLL_PL_]

I think it might be better to use simple class with singleton pattern 🙂

class mySession
{
  private static $oInstance=null;

  public static function getInstance()
  {
    if(self::$oInstance==null)
    {
       self::$oInstance==&new self();
    }
    return self::$oInstance;
  }

  private function __construct()
  { 
   session_start();
  }

  public function __set($name,$value)
  {
    $_SESSION[$name]=$value;
  }

  public function __get($name)
  {
     return isset($_SESSION[$name]) ? $_SESSION[$name] : null ;
  }
}

That is very simple example but u can fit this simple class to your needs 🙂