#php sessions

In PHP, a session provides a way to store visitor preferences on a web server in the form of variables that can be used on multiple pages. Unlike cookies, variable information is not saved on the user's computer. The information is retrieved from the web server when a session is opened at the beginning of each web page. The session expires when the web page is closed.

Some information, such as usernames and authentication details, is better stored in cookies as they are needed before the site is opened. Sessions, however, offer better security for the personal information needed after the site is started, and they provide a level of customization for site visitors.

Call this example code mypage.php.

The first thing this sample code does is open the session with the session_start () function. It then sets the session variables - color, size, and shape - to the red, small and round respectively.

As with cookies, the session_start () code must be in the header of the code, and you cannot send anything to the browser before it. It's best to just put it right after

The session sets a small cookie on the user's computer to act as a key. It's just a key; no personal information is included in the cookie. The web server looks for that key when a user enters the URL of one of their hosted websites. If the server finds the key, the session and the information it contains for the first page of the site open. If the server does not find the key, the user continues to the site, but the information stored on the server is not transferred to the site.

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Using session variables

Each page on the site that needs access to the information stored in the session must have the session_start () function at the top of the code for that page. Note that the values for the variables are not specified in the code.

Call this code mypage2.php.

All values are stored in the $ _SESSION array, which you will find here. Another way to show this is to run this code:

You can also store an array in the session. Go back to our mypage.php file and edit it a bit to do it:

Now let's run this at mypage2.php to view our new information:

Modify or Remove a Session

This code shows you how to edit or delete individual session variables or the entire session. To change a session variable, simply reset it to something else by typing right over it. You can use unset () to remove a single variable or use session_unset () to remove all variables for a session. You can also use session_destroy () to completely destroy the session.

By default, a session lasts until the user closes the browser. This option can be changed in the php.ini file on the webserver by changing 0 in session.cookie_lifetime = 0 to the number of seconds you want the session to run or using session_set_cookie_params ().

PHP Sessions

What is a PHP Session?

PHP Sessions allow web pages to be treated as a group, allowing variables to be shared between different pages. One of the weaknesses of cookies is that the cookie is stored on the user’s computer (and by user we mean the person…