session_start
(PHP 4 )
session_start -- Initialize session data
Description
bool session_start ( void )
session_start() creates a session or resumes the current
one based on the current session id that's being passed
via a request, such as GET, POST, or a cookie.
This function always returns TRUE.
Note: If you are using cookie-based sessions, you must
call session_start() before anything is outputted to the
browser.
Example 1. A session example: page1.php
<?php
// page1.php
session_start();
echo 'Welcome to page #1';
$_SESSION['favcolor'] = 'green';
$_SESSION['animal'] = 'cat';
$_SESSION['time'] = time();
// Works if session cookie was accepted
echo '<br /><a href="page2.php">page
2</a>';
// Or maybe pass along the session id, if needed
echo '<br /><a href="page2.php?' . SID . '">page
2</a>';
?>
After viewing page1.php, the second page page2.php will
magically contain the session data. Read the session reference
for information on propagating session ids as it, for example,
explains what the constant SID is all about.
Example 2. A session example: page2.php
<?php
// page2.php
session_start();
echo 'Welcome to page #2<br />';
echo $_SESSION['favcolor']; // green
echo $_SESSION['animal']; // cat
echo date('Y m d H:i:s', $_SESSION['time']);
// You may want to use SID here, like we did in page1.php
echo '<br /><a href="page1.php">page
1</a>';
?>
If you want to use a named session, you must call session_name()
before calling session_start().
session_start() will register internal output handler for
URL rewriting when trans-sid is enabled. If a user uses
ob_gzhandler or like with ob_start(), the order of output
handler is important for proper output. For example, user
must register ob_gzhandler before session start.
Note: Use of zlib.output_compression is recommended rather
than ob_gzhandler()
Note: As of PHP 4.3.3, calling session_start() while the
session has already been started will result in an error
of level E_NOTICE. Also, the second session start will simply
be ignored.
See also $_SESSION, session.auto_start, and session_id().
