This function replaces the current session id with a newly generated one .

Syntax: session_regenerate_id()

Description:

session_regenerate_id() will replace the current session id with a new one, and keep the current session information.

Example:
Code:

session_start();

$old_sessionid = session_id();

session_regenerate_id();

$new_sessionid   session_id();

echo  "Old Session: $old_sessionid";
echo "New Session: $new_sessionid";

Explanation:

By default, the cookies are set to be deleted when the browser is closed. We can override that default by setting a time for the cookie’s expiration but there may be occasions when you need to delete a cookie before the user closes his browser, and before its expiration time arrives. To do so, you should assure that the expiration date is in the past. To destroy the cookie, simply use setcookie.

Example:
Code:

// set the expiration date   to one hour  ago
setcookie("lastVisit",   "date("G:i - m/d/y")", time()-3600);

Explanation:

It sets expiration time 1 hour ago.

The PHP $_COOKIE variable is used to retrieve a cookie value.

Syntax: $_COOKIE['cookie name']

Description:

The parameter “cookie name” is Required.

Example:
Code:

if(isset($_COOKIE['lastVisit']))
   {
 $last = $_COOKIE['lastVisit'];
 echo "You last visited on ". $last;
 }
 else
 {
 echo "Welcome to our site!";
 }

Explanation:

This code first checks if the cookie exists. If it does, it tells them when they last visited. If they are new, it skips this and prints a welcome message.

This function is used to set a cookie.

A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user’s computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.

Syntax: setcookie(name, value, expire, path, domain,secure,httponly).

Description:

When you create a cookie,using the function setcookie,the parameters name, value, expire, path, domain are used.All the parameters except the name argument are optional.

The first parameter “name” is Required. It specifies the name of your cookie. You will use this name to later retrieve your cookie, so don’t forget it!

The second parameter “value” is Optional. It specifies the value that is stored in your cookie. Common values are username(string) and last visit(date).

The third parameter “expiration” is Optional The date when the cookie will expire and be deleted. If you do not set this expiration date, then it will be treated as a session cookie and be removed when the browser is restarted.

The fourth parameter “path” is Optional. It specifies on the server in which the cookie will be available on. If set to ‘/’, the cookie will be available within the entire domain. If set to ‘/example/’, the cookie will only be available within the /example/ directory and all sub-directories such as /example/examp/ of domain. The default value is the current directory that the cookie is being set in.
domain.

The fifth parameter “domain” is Optional.It specifies that the cookie is available to. To make the cookie available on all subdomains of example.com (including example.com itself) then you’d set it to ‘.example.com’. Although some browsers will accept cookies without the initial ., » RFC 2109 requires it to be included. Setting the domain to ‘www.example.com’ or ‘.www.example.com’ will make the cookie only available in the www subdomain.

The sixth parameter “secure” is Optional.It specifies that the cookie should only be transmitted over a secure HTTPS connection from the client. When set to TRUE, the cookie will only be set if a secure connection exists. On the server-side, it’s on the programmer to send this kind of cookie only on secure connection (e.g. with respect to $_SERVER["HTTPS"]).

The seventh parameter “httponly” is Optional.It specifies When TRUE the cookie will be made accessible only through the HTTP protocol. This means that the cookie won’t be accessible by scripting languages, such as JavaScript. This setting can effectively help to reduce identity theft through XSS attacks (although it is not supported by all browsers). Added in PHP 5.2.0. TRUE or FALSE.

Example:
Code:

//Calculate 30 days in the future
//seconds * minutes * hours * days + current time
$inOneMonth = 60 * 60 * 24 * 30 + time();
setcookie('lastVisit', date("G:i - m/d/y"), $inOneMonth);

Explanation:

In the above example we have created a cookie that stores the user’s last visit. We want to ignore people that take longer than one month to return to the site, so we have set the cookie’s expiration date to one month in the future!

This function Unregister a global variable from the current session.

Syntax: session_unregister ( string name )

Description:

The parameter “string name” is specified to be unregistered.

This function unregisters a session variable registered with session_register(). If $_SESSION was used to register the session variable, use unset() to unregister it.

Example:
Code:

session_start();
session_register("session_variable");
$session_variable   = "xyz123";
print "session_variable: " . $session_variable;
session_unregister("session_variable");

This function register one or more global variables with the current session.

Syntax: session_register ( mixed name [, mixed ...] )

Description:

session_register() accepts a variable number of arguments, For each name, session_register() registers the global variable with that name in the current session. It does not assign a value to the session variable.that this function takes the name of a variable as argument, not the variable itself. You can use session_unregister() to remove variables from the session, for example, when the user removes a product item from the shopping cart.

Example:
Code:

session_start();
session_register("session_variable");
$session_variable = "xyz123";
print "session_variable: " . $session_variable;
session_unregister("session_variable");

Output:

session_variable: xyz123

It free all session variables.

session_unset ( )

Description:

The unset() function is used to free the specified session variable.

Example:
Code:

 // you  have to open the session to be able to modify or remove it
 session_start(); 

 // or this would remove all the variable in the session
 session_unset(); 

Explanation:

This function would remove all the variable in the session.

It Get or set the current session id.

Syntax: session_id (id )

Description:

The parameter “id” is Optional. If id is specified, it will replace the current session id.

It returns the session ID created with session_start(). It can also be used to change the session ID.

Example:
Code:

session_id();
session_start();
print  "My session ID is: " . session_id();
session_destroy();

Output:

My session ID is: balv2nv98i27j5drl7c720mjs7

It destroys all stored data registered with the current session.

Syntax: session_destroy()

Description:

This function will reset your session and you will lose all your stored session data.

Example:
Code:

 session_start(); 

 // destroy the session
 session_destroy();
 

It Get or set the current cache limiter.

Syntax: session_cache_limiter ( string cache_limiter )

Description:

It returns the name of the current cache limiter. If cache_limiter is specified, the name of the current cache limiter is changed to the new value.

The cache limiter defines which cache control HTTP headers are sent to the client. These headers determine the rules by which the page content may be cached by the client and intermediate proxies. Setting the cache limiter to nocache disallows any client/proxy caching. A value of public permits caching by proxies and the client, whereas private disallows caching by proxies and permits the client to cache the contents.

Example:
Code:

/* set the cache limiter to 'private' */

session_cache_limiter('private');
$cache_limit = session_cache_limiter();

echo "The cache limit is set to $cache_limit";

Output:

The cache limit is set to private

It returns current cache expire.

Syntax: session_cache_expire ($new_cache_expire)

Description:

The parameter “$new_cache_expire” is given, the current cache expire is replaced with new_cache_expire.

It returns the current setting of session.cache_expire. The value returned should be read in minutes, defaults to 180.

Example:
Code:

/* set the cache limiter to 'private' */

session_cache_limiter('private');
$cache_limiter  = session_cache_limiter();

/*   set the cache expire to 40 minutes */
session_cache_expire(40);
$cache_expire  = session_cache_expire();

/* start the session */

session_start();

echo "The cache is set to $cache_limiter";
echo "The cached session pages expire after $cache_expire minutes";

Output:

The cache is set to private
The cached session pages expire after 40 minutes