$_SESSION
An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.
Notes
Note:
This is a ‘superglobal’, or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
See Also
User Contributed Notes 8 notes
Creating New Session
==========================
session_start ();
/*session is started if you don’t write this line can’t use $_Session global variable*/
$_SESSION [ «newsession» ]= $value ;
?>
Getting Session
==========================
session_start ();
/*session is started if you don’t write this line can’t use $_Session global variable*/
$_SESSION [ «newsession» ]= $value ;
/*session created*/
echo $_SESSION [ «newsession» ];
/*session was getting*/
?>
Updating Session
==========================
session_start ();
/*session is started if you don’t write this line can’t use $_Session global variable*/
$_SESSION [ «newsession» ]= $value ;
/*it is my new session*/
$_SESSION [ «newsession» ]= $updatedvalue ;
/*session updated*/
?>
Deleting Session
==========================
session_start ();
/*session is started if you don’t write this line can’t use $_Session global variable*/
$_SESSION [ «newsession» ]= $value ;
unset( $_SESSION [ «newsession» ]);
/*session deleted. if you try using this you’ve got an error*/
?>
Be carefull with $_SESSION array elements when you have the same name as a normal global.
The following example leads to unpredictable behaviour of the $wppa array elements, some are updated by normal code, some not, it is totally unpredictable what happens.
global $wppa ;
$wppa = array( ‘elm1’ => ‘value1’ , ‘elm2’ => ‘value2’ , . etc . );
if ( ! session_id () ) @ session_start ();
if ( ! isset( $_SESSION [ ‘wppa’ ]) $_SESSION [ ‘wppa’ ] = array();
if ( ! isset( $_SESSION [ ‘wppa’ ][ ‘album’ ]) ) $_SESSION [ ‘wppa’ ][ ‘album’ ] = array();
$_SESSION [ ‘wppa’ ][ ‘album’ ][ 1234 ] = 1 ;
print_r ( $_SESSION );
?>
This will most likely display Array ( [wppa] => Array ( [album] => Array ( [1234] => 1 ) [elm1] => ‘newvalue1’ [elm2] => ‘value2’ . etc .
But setting $wppa[‘elm1’] to another value or referring to it gives unpredictable results, maybe ‘value1’, or ‘newvalue1’.
The most strange behaviour is that not all elements of $wppa[xx] show up as $_SESSION[‘wppa’][xx].
Please note that if you have register_globals to On, global variables associated to $_SESSION variables are references, so this may lead to some weird situations.
$_SESSION [ ‘test’ ] = 42 ;
$test = 43 ;
echo $_SESSION [ ‘test’ ];
?>
Load the page, OK it displays 42, reload the page. it displays 43.
The solution is to do this after each time you do a session_start() :
if ( ini_get ( ‘register_globals’ ))
foreach ( $_SESSION as $key => $value )
if (isset( $GLOBALS [ $key ]))
unset( $GLOBALS [ $key ]);
>
>
Regarding array keys, from http://php.net/manual/en/language.types.array.php, «Strings containing valid integers will be cast to the integer type».
The manual on $_SESSION says «An associative array». So an associative array is expected literally. It does no one any good if this bit of important info about accessing and storing session data remains buried in manual comments.
Session variables with a single number will not work, however «1a» will work, as will «a1» and even a just single letter, for example «a» will also work.
session_start ();
$_SESSION [ «1» ] = «LOGGED» ;
?>
2nd page
session_start ();
$_SESSION [ «a» ] = «LOGGED» ;
?>
2nd page
session_start ();
$_SESSION [ «a1» ] = «LOGGED» ;
?>
2nd page
Example from PHP.net manual on Session variables
$_SESSION [ 1 ][ 1 ] = ‘cake’ ; // fails
session_name
session_name() returns the name of the current session. If name is given, session_name() will update the session name and return the old session name.
If a new session name is supplied, session_name() modifies the HTTP cookie (and output content when session.transid is enabled). Once the HTTP cookie is sent, session_name() raises error. session_name() must be called before session_start() for the session to work properly.
The session name is reset to the default value stored in session.name at request startup time. Thus, you need to call session_name() for every request (and before session_start() is called).
Parameters
The session name references the name of the session, which is used in cookies and URLs (e.g. PHPSESSID ). It should contain only alphanumeric characters; it should be short and descriptive (i.e. for users with enabled cookie warnings). If name is specified and not null , the name of the current session is changed to its value.
The session name can’t consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.
Return Values
Returns the name of the current session. If name is given and function updates the session name, name of the old session is returned, or false on failure.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | name is nullable now. |
| 7.2.0 | session_name() checks session status, previously it only checked cookie status. Therefore, older session_name() allows to call session_name() after session_start() which may crash PHP and may result in misbehaviors. |
Examples
Example #1 session_name() example
/* set the session name to WebsiteID */
$previous_name = session_name ( «WebsiteID» );
echo «The previous session name was $previous_name
» ;
?>
See Also
User Contributed Notes 10 notes
This may sound no-brainer: the session_name() function will have no essential effect if you set session.auto_start to «true» in php.ini . And the obvious explanation is the session already started thus cannot be altered before the session_name() function—wherever it is in the script—is executed, same reason session_name needs to be called before session_start() as documented.
I know it is really not a big deal. But I had a quite hard time before figuring this out, and hope it might be helpful to someone like me.
if you try to name a php session «example.com» it gets converted to «example_com» and everything breaks.
don’t use a period in your session name.
Remember, kids—you MUST use session_name() first if you want to use session_set_cookie_params() to, say, change the session timeout. Otherwise it won’t work, won’t give any error, and nothing in the documentation (that I’ve seen, anyway) will explain why.
Thanks to brandan of bildungsroman.com who left a note under session_set_cookie_params() explaining this or I’d probably still be throwing my hands up about it.
For those wondering, this function is expensive!
On a script that was executing in a consistent 0.0025 seconds, just the use of session_name(«foo») shot my execution time up to ~0.09s. By simply sacrificing session_name(«foo»), I sped my script up by roughly 0.09 seconds.
As Joseph Dalrymple said, adding session_name do slow down a little bit the execution time.
But, what i’ve observed is that it decreased the fluctuation between requests.
Requests on my script fluctuated between 0,045 and 0,022 seconds. With session_name(«myapp»), it goes to 0,050 and 0,045. Not a big deal, but that’s a point to note.
For those with problems setting the name, when session.auto_start is set to 1, you need to set the session.name on php.ini!
Hope this is not out of php.net noting scope.
session_name(‘name’) must be set before session_start() because the former changes ini settings and the latter reads them. For the same reason session_set_cookie_params($options) must be set before session_start() as well.
I find it best to do the following.
function is_session_started()
if (php_sapi_name() === ‘cli’)
return false;
if (version_compare(phpversion(), ‘5.4.0’, ‘>=’))
return session_status() === PHP_SESSION_ACTIVE;
return session_id() !== »;
>
if (!is_session_started()) session_name($session_name);
session_set_cookie_params($cookie_options);
session_start();
>
Always try to set the prefix for your session name attribute to either `__Host-` or `__Secure-` to benefit from Browsers improved security. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie#attributes
Also, if you have auto_session enabled, you must set this name in session.name in your config (php.ini, htaccess, etc)
The description that session_name() gets and/or sets the name of the current session is technically wrong. It does nothing but deal with the value originally supplied by the session.name value within the php.ini file.
Thus:-
$name = session_name();
is functionally equivalent to
$name = ini_get(‘session.name’);
and
session_name(‘newname);
is functionally equivalent to
ini_set(‘session.name’,’newname’);
This also means that:
$old_name = session_name(‘newname’);
is functionally equivalent to
$old_name = ini_set(‘session.name’,’newname’);
The current value of session.name is not attached to a session until session_start() is called. Once session_start() has used session.name to lookup the session_id() in the cookie data the name becomes irrelevant as all further operations on the session data are keyed by the session_id().
Note that changing session.name while a session is currently active will not update the name in any session cookie. The new name does not take effect until the next call to session_start(), and this requires that the current session, which was created with the previous value for session.name, be closed.
The description has recently been modified to contain the statement «When new session name is supplied, session_name() modifies HTTP cookie». This is not correct as session_name() has never modified any cookie data. A change in session.name does not become effective until session_start() is called, and it is session_start() that creates the cookie if it does not already exist.
See the following bug report for details: https://bugs.php.net/bug.php?id=76413
One gotcha I have noticed with session_name is that it will trigger a WARNING level error if the cookie or GET/POST variable value has something other than alphanumeric characters in it. If your site displays warnings and uses PHP sessions this may be a way to enumerate at least some of your scripts:
Warning: session_start(): The session id contains invalid characters, valid characters are only a-z, A-Z and 0-9 in /some/path/foo.php on line 666
I did not see anything in the docs suggesting that one had to sanitize the PHP session ID values before opening the session but that appears to be the case.
Unfortunately session_name() always returns true so you have to actually get to the point of assigning variables values before you know whether you have been passed bad session data (as far as I can see). After the error has been generated in other words.
- Session Functions
- session_abort
- session_cache_expire
- session_cache_limiter
- session_commit
- session_create_id
- session_decode
- session_destroy
- session_encode
- session_gc
- session_get_cookie_params
- session_id
- session_module_name
- session_name
- session_regenerate_id
- session_register_shutdown
- session_reset
- session_save_path
- session_set_cookie_params
- session_set_save_handler
- session_start
- session_status
- session_unset
- session_write_close