Check if PHP session has already started

Question

I have a PHP file that is sometimes called from a page that has started a session and sometimes from a page that doesn\'t have session started. Therefore when I have s

Answer 1

For versions of PHP prior to PHP 5.4.0:

if(session_id() == '') {
    // session isn't started
}

Though, IMHO, you should really think about refactoring your session management code if you don't know whether or not a session is started...

That said, my opinion is subjective, and there are situations (examples of which are described in the comments below) where it may not be possible to know if the session is started.

Answer 2

Recommended way for versions of PHP >= 5.4.0 , PHP 7

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

Reference: http://www.php.net/manual/en/function.session-status.php

For versions of PHP < 5.4.0

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