Specifications

It is generally easier to compile with --enable-trans-sid, where possible. Note also that the

SID constant will only work like this if you have configured PHP with --enable-track-vars.

Implementing Simple Sessions

The basic steps of using sessions are

• Starting a session

• Registering session variables

• Using session variables

• Deregistering variables and destroying the session

Note that these steps don’t necessarily all happen in the same script, and some of them will

happen in multiple scripts. Let’s talk about each of these steps in turn.

Starting a Session

Before you can use session functionality, you need to actually begin a session. There are three

ways you can do this.

The first, and simplest, is to begin a script with a call to the session_start() function:

session_start();

This function checks to see if there is already a current session ID. If not, it will create one. If

one already exists, it essentially loads the registered session variables so that you can use them.

It’s a good idea to call session_start() at the start of all your scripts that use sessions.

Second, a session will be started when you try to register a session variable (see the next sec-

tion).

The third way you can begin a session is to set PHP to start one automatically when someone

comes to your site. You can do this with the

session.auto_start option in your php.ini

file—we’ll look at this when we discuss configuration.

Registering Session Variables

In order for a variable to be tracked from one script to another, you need to register it with a

call to session_register(). For example, to register the variable $myvar, you could use the

following code

$myvar = 5;

session_register(“myvar”);

Using Session Control in PHP

HAPTER 20

USING SESSION

ONTROL IN

PHP

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