$_SESSION

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

    $_SESSION — Session variables

    Description

    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

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    User Contributed Notes 6 notes

    up
    101
    Tugrul
    9 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*/
    ?>
    up
    9
    bohwaz
    15 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]);
    }
    }

    ?>
    up
    0
    opajaap at opajaap dot nl
    10 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].
    up
    -40
    jherry at netcourrier dot com
    15 years ago
    You may have trouble if you use '|' in the key:

    $_SESSION["foo|bar"] = "fuzzy";

    This does not work for me. I think it's because the serialisation of session object is using this char so the server reset your session when it cannot read it.

    To make it work I replaced '|' by '_'.
    up
    -67
    charlese at cvs dot com dot au
    15 years ago
    I was having troubles with session variables working in some environments and being seriously flaky in others. I was using $_SESSION as an array. It works properly when I used $_SESSION as pointers to arrays. As an example the following code works in some environments and not others.

    <?php
    //Trouble if I treate $form_convert and $_SESSION['form_convert'] as unrelated items
    $form_convert=array();
    if (isset(    $_SESSION['form_convert'])){
    $form_convert=$_SESSION['form_convert'];
    }
    }
    ?>
    The following works well.
    <?php
    if (isset($_SESSION['form_convert'])){
    $form_convert = $_SESSION['form_convert'];
    }else{
    $form_convert = array();
    $_SESSION['form_convert']=$form_convert;
    }
    ?>
    up
    -46
    ms at meilenstein dot ms
    5 years ago
    I would be wary to use PHP Sessions for application-critical tasks. So far, I have had very troubling experiences with random loss of session data, as described in these bug reports:

    https://bugs.php.net/bug.php?id=19022
    https://bugs.php.net/bug.php?id=19029
    https://bugs.php.net/bug.php?id=70584
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