$_SESSION

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

$_SESSION — Variables de sesión

Descripción

Es un array asociativo que contiene variables de sesión disponibles para el script actual. Ver la documentación de Funciones de sesión para más información sobre su uso.

Notas

Nota:
Esto es una 'superglobal', o variable global automática. Esto significa simplemente que esta variable está disponible en todos los contextos del script. No es necesario hacer global $variable; para acceder a ella en las funciones o los métodos.

Ver también

session_start() - Inicia una nueva sesión o reanuda una sesión existente

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User Contributed Notes 3 notes

down

102

Tugrul ¶

10 years ago

Creating New Session

==========================

<?php 

session_start();

/*session is started if you don't write this line can't use $_Session  global variable*/

$_SESSION["newsession"]=$value;

?>

Getting Session

==========================

<?php 

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

==========================

<?php 

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

==========================

<?php 

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*/

?>

down

opajaap at opajaap dot nl ¶

11 years ago

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.

<?php
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;

$wppa['elm1'] = 'newvalue1';

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].

down

bohwaz ¶

16 years ago

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.

<?php

session_start();

$_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() :

<?php

if (ini_get('register_globals'))
{
    foreach ($_SESSION as $key=>$value)
    {
        if (isset($GLOBALS[$key]))
            unset($GLOBALS[$key]);
    }
}

?>

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