$_SESSION

$HTTP_SESSION_VARS [已弃用]

$_SESSION -- $HTTP_SESSION_VARS [已弃用] — Session 变量

说明

当前脚本可用 SESSION 变量的数组。更多关于如何使用的信息，参见 Session 函数文档。

$HTTP_SESSION_VARS 包含相同的信息，但它不是一个超全局变量。 (注意 $HTTP_SESSION_VARS 和 $_SESSION 是不同的变量，PHP 处理它们的方式不同)

更新日志

版本	说明
4.1.0	引入 `$_SESSION` ，弃用 `$HTTP_SESSION_VARS` 。

注释

Note:

“Superglobal”也称为自动化的全局变量。这就表示其在脚本的所有作用域中都是可用的。不需要在函数或方法中用 global $variable; 来访问它。

参见

session_start() - 启动新会话或者重用现有会话

用户评论:

[#1] Tugrul [2015-03-09 17:04:49]

Creating New Session
==========================
<?php session_start(); $_SESSION["newsession"]=$value; ?>
Getting Session
==========================
<?php session_start(); $_SESSION["newsession"]=$value; echo $_SESSION["newsession"]; ?>
Updating Session
==========================
<?php session_start(); $_SESSION["newsession"]=$value; $_SESSION["newsession"]=$updatedvalue; ?>
Deleting Session
==========================
<?php session_start(); $_SESSION["newsession"]=$value; unset($_SESSION["newsession"]); ?>

Reference: http://gencbilgin.net/php-session-kullanimi.html

[#2] Aswad [2014-11-27 05:01:16]

My session variable dies when it switches on some other page and I can't get it's value on other pages.

$_SESSION["username"]=filter_input(INPUT_POST,"username");

and on the top of every page, I have started the session by using this statement

session_start();

Can anybody help me? I can't use 1 hidden field in every page just to store the value of 1 attribute. What if I need many variables then using hidden fields for all of them will be a bad approach.

Thanks.

[#3] Fred [2013-09-07 03:09:40]

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.

(Invalid)
1st page

<?php session_start(); $_SESSION["1"] = "LOGGED"; ?>

2nd page

<?php session_start(); echo $_SESSION["1"]; ?>

---------------------------------------------------------------

(Valid)
1st page

<?php session_start(); $_SESSION["a"] = "LOGGED"; ?>

2nd page

<?php session_start(); echo $_SESSION["a"]; ?>

---------------------------------------------------------------

(Valid)
1st page

<?php session_start(); $_SESSION["a1"] = "LOGGED"; ?>

2nd page

<?php session_start(); echo $_SESSION["a1"]; ?>

---------------------------------------------------------------

Example from PHP.net manual on Session variables

<?php $_SESSION[1][1] = 'cake'; // fails $_SESSION['v1'][2] = 'cake'; // works ?>

Source: http://php.net/manual/en/language.types.array.php

[#4] opajaap at opajaap dot nl [2013-08-31 11:51:39]

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].

[#5] Miller [2013-08-12 20:48:05]

I wrote a little page for controlling/manipulating the session. Obviously, never use this on a production server, but I use it on my localhost to assist me in checking and changing session values on the fly.

Again, it makes use of eval() and exposes the session, so never use this on a web server.

<?php error_reporting(E_ALL); session_start(); if (isset($_POST['session'])) { $session = eval("return {$_POST['session']};"); if (is_array($session)) { $_SESSION = $session; header("Location: {$_SERVER['PHP_SELF']}?saved"); } else { header("Location: {$_SERVER['PHP_SELF']}?error"); } } $session = htmlentities(var_export($_SESSION, true)); ?>
<!DOCTYPE html>
<html lang="en-US">
<head>
<meta charset="UTF-8">
<title>Session Variable Management</title>
<style>
textarea { font: 12px Consolas, Monaco, monospace; padding: 2px; border: 1px solid #444444; width: 99%; }
.saved, .error { border: 1px solid #509151; background: #DDF0DD; padding: 2px; }
.error { border-color: #915050; background: #F0DDDD; }
</style>
</head>
<body>
<h1>Session Variable Management</h1>
<?php if (isset($_GET['saved'])) { ?>
<p class="saved">The session was saved successfully.</p>
<?php } else if (isset($_GET['error'])) { ?>
<p class="error">The session variable did not parse correctly.</p>
<?php } ?>
<form method="post">
<textarea name="session" rows="<?php echo count(preg_split("/\n|\r/", $session)); ?#=#>"><?php echo $session; ?></textarea>
<input type="submit" value="Update Session">
</form>
</body>
</html>

[#6] pike-php at kw dot nl [2011-02-07 06:00:29]

When accidently assigning a unset variable to $_SESSION, like

$_SESSION['foo'] = $bar

while $bar was not defined, I got the following error message:

"Warning: Unknown(): Your script possibly relies on a session side-effect which existed until PHP 4.2.3. Please be advised that the session extension does not consider global variables as a source of data, unless register_globals is enabled. "

The errormessage was quite unrelated and got me off-track. The real error was, $bar was not defined.

[#7] Dave [2009-11-17 14:05:47]

If you deploy php code and cannot control whether register_globals is off, place this snippet in your code to prevent session injections:

<?php if (isset($_REQUEST['_SESSION'])) die("Get lost Muppet!"); ?>

[#8] charlese at cvs dot com dot au [2009-07-04 18:47:26]

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; } ?>

[#9] bohwaz [2008-08-31 14:43:37]

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]); } } ?>

[#10] Steve Clay [2008-08-17 06:28:18]

Unlike a real PHP array, $_SESSION keys at the root level must be valid variable names.

<?php $_SESSION[1][1] = 'cake'; // fails $_SESSION['v1'][1] = 'cake'; // works ?>

I imagine this is an internal limitation having to do with the legacy function session_register(), where the registered global var must similarly have a valid name.

[#11] jherry at netcourrier dot com [2008-08-01 16:16:05]

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 '_'.