PHP 8.1.15 Released!

session_unset

(PHP 4, PHP 5, PHP 7, PHP 8)

session_unset释放所有的会话变量

说明

session_unset(): void

session_unset() 会释放当前会话注册的所有会话变量。

返回值

没有返回值。

注释

注意:

如果使用的是 $_SESSION (或者PHP 4.0.6或更早版本的 $HTTP_SESSION_VARS ) ,请使用 unset() 去 注销会话变量,即 unset ($_SESSION['varname']);.

警告

请不要使用unset($_SESSION)来释放整个$_SESSION, 因为它将会禁用通过全局$_SESSION去注册会话变量

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User Contributed Notes 4 notes

up
36
tim at leethost dot com
11 years ago
I was having a problem clearing all session variables, deleting the session, and creating a new session without leaving old session stuff behind in all browsers.  The below code is perfect for a logout script to totally delete everything and start new.  It even works in Chrome which seems to not work as other browsers when trying do logout and start a new session.

<?php
    session_start
();
   
session_unset();
   
session_destroy();
   
session_write_close();
   
setcookie(session_name(),'',0,'/');
   
session_regenerate_id(true);
?>
up
22
jerry
7 years ago
The difference between both session_unset and session_destroy is as follows:

session_unset just clears out the session for usage. The session is still on the users computer. Note that by using session_unset, the variable still exists. session_unset just remove all session variables. it does not destroy the session....so the session would still be active.

Using session_unset in tandem with session_destroy however, is a much more effective means of actually clearing out data. As stated in the example above, this works very well, cross browser. session_destroy is destroy the session. session_destroy() to kill all session information.....This is the more secure function to use.
up
-15
Jeroen
18 years ago
note to Jason: I don't know the exact mechanics of it (since I'm quite new to sessions) but I think you need to use session_unset() BEFORE you can use session_destroy() at all.  I thought that session_unset() was for scripted variables, and session_destroy() just for anything saved on your side regarding the session.
up
-30
zach at zkwarta dot com
17 years ago
The difference between both session_unset and session_destroy is as follows:

session_unset just clears out the sesison for usage. The session is still on the users computer. Note that by using session_unset, the variable still exists.

Using session_unset in tandem with session_destroy however, is a much more effective means of actually clearing out data. As stated in the example above, this works very well, cross browser:

session_unset();
session_destroy();

I noticed that in firefox, one could simply use sesison_unset and the session would be cleared. When trying this on IE, I was horrified to find out that the data was still there, so I had to use session destroy.
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