PHP: $_SESSION - Manual (original) (raw)
(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 doglobal $variable; to access it within functions or methods.
Found A Problem?
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*/ <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mrow></mrow><mi>S</mi></msub><mi>E</mi><mi>S</mi><mi>S</mi><mi>I</mi><mi>O</mi><mi>N</mi><mo stretchy="false">[</mo><mi mathvariant="normal">"</mi><mi>n</mi><mi>e</mi><mi>w</mi><mi>s</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>i</mi><mi>o</mi><mi>n</mi><mi mathvariant="normal">"</mi><mo stretchy="false">]</mo><mo>=</mo></mrow><annotation encoding="application/x-tex">_SESSION["newsession"]=</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord"><span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3283em;"><span style="top:-2.55em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight" style="margin-right:0.05764em;">S</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.05764em;">ESS</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal" style="margin-right:0.10903em;">ON</span><span class="mopen">[</span><span class="mord">"</span><span class="mord mathnormal">n</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">sess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord">"</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span></span></span></span>value;
?>
Getting Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session global variable*/ <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mrow></mrow><mi>S</mi></msub><mi>E</mi><mi>S</mi><mi>S</mi><mi>I</mi><mi>O</mi><mi>N</mi><mo stretchy="false">[</mo><mi mathvariant="normal">"</mi><mi>n</mi><mi>e</mi><mi>w</mi><mi>s</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>i</mi><mi>o</mi><mi>n</mi><mi mathvariant="normal">"</mi><mo stretchy="false">]</mo><mo>=</mo></mrow><annotation encoding="application/x-tex">_SESSION["newsession"]=</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord"><span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3283em;"><span style="top:-2.55em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight" style="margin-right:0.05764em;">S</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.05764em;">ESS</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal" style="margin-right:0.10903em;">ON</span><span class="mopen">[</span><span class="mord">"</span><span class="mord mathnormal">n</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">sess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord">"</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span></span></span></span>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*/ <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mrow></mrow><mi>S</mi></msub><mi>E</mi><mi>S</mi><mi>S</mi><mi>I</mi><mi>O</mi><mi>N</mi><mo stretchy="false">[</mo><mi mathvariant="normal">"</mi><mi>n</mi><mi>e</mi><mi>w</mi><mi>s</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>i</mi><mi>o</mi><mi>n</mi><mi mathvariant="normal">"</mi><mo stretchy="false">]</mo><mo>=</mo></mrow><annotation encoding="application/x-tex">_SESSION["newsession"]=</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord"><span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3283em;"><span style="top:-2.55em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight" style="margin-right:0.05764em;">S</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.05764em;">ESS</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal" style="margin-right:0.10903em;">ON</span><span class="mopen">[</span><span class="mord">"</span><span class="mord mathnormal">n</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">sess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord">"</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span></span></span></span>value;
/*it is my new session*/ <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mrow></mrow><mi>S</mi></msub><mi>E</mi><mi>S</mi><mi>S</mi><mi>I</mi><mi>O</mi><mi>N</mi><mo stretchy="false">[</mo><mi mathvariant="normal">"</mi><mi>n</mi><mi>e</mi><mi>w</mi><mi>s</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>i</mi><mi>o</mi><mi>n</mi><mi mathvariant="normal">"</mi><mo stretchy="false">]</mo><mo>=</mo></mrow><annotation encoding="application/x-tex">_SESSION["newsession"]=</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord"><span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3283em;"><span style="top:-2.55em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight" style="margin-right:0.05764em;">S</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.05764em;">ESS</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal" style="margin-right:0.10903em;">ON</span><span class="mopen">[</span><span class="mord">"</span><span class="mord mathnormal">n</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">sess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord">"</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span></span></span></span>updatedvalue;
/*session updated*/
?>
Deleting Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session global variable*/ <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msub><mrow></mrow><mi>S</mi></msub><mi>E</mi><mi>S</mi><mi>S</mi><mi>I</mi><mi>O</mi><mi>N</mi><mo stretchy="false">[</mo><mi mathvariant="normal">"</mi><mi>n</mi><mi>e</mi><mi>w</mi><mi>s</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>i</mi><mi>o</mi><mi>n</mi><mi mathvariant="normal">"</mi><mo stretchy="false">]</mo><mo>=</mo></mrow><annotation encoding="application/x-tex">_SESSION["newsession"]=</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord"><span></span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height:0.3283em;"><span style="top:-2.55em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathnormal mtight" style="margin-right:0.05764em;">S</span></span></span></span><span class="vlist-s"></span></span><span class="vlist-r"><span class="vlist" style="height:0.15em;"><span></span></span></span></span></span></span><span class="mord mathnormal" style="margin-right:0.05764em;">ESS</span><span class="mord mathnormal" style="margin-right:0.07847em;">I</span><span class="mord mathnormal" style="margin-right:0.10903em;">ON</span><span class="mopen">[</span><span class="mord">"</span><span class="mord mathnormal">n</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.02691em;">w</span><span class="mord mathnormal">sess</span><span class="mord mathnormal">i</span><span class="mord mathnormal">o</span><span class="mord mathnormal">n</span><span class="mord">"</span><span class="mclose">]</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span></span></span></span>value;
unset($_SESSION["newsession"]);
/*session deleted. if you try using this you've got an error*/
?>17 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 <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>k</mi><mi>e</mi><mi>y</mi><mo>=</mo><mo>></mo></mrow><annotation encoding="application/x-tex">key=></annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord mathnormal" style="margin-right:0.03148em;">k</span><span class="mord mathnormal" style="margin-right:0.03588em;">ey</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=></span></span></span></span>value)
{
if (isset($GLOBALS[$key]))
unset($GLOBALS[$key]);
}
}
?>