session_name

(PHP 4, PHP 5, PHP 7)

session_name — Get and/or set the current session name

Description

string session_name ([ string $name ] )

session_name() returns the name of the current session. If name is given, session_name() will update the session name and return the old session name.

The session name is reset to the default value stored in session.name at request startup time. Thus, you need to call session_name() for every request (and before session_start() or session_register() are called).

Parameters

name

The session name references the name of the session, which is used in cookies and URLs (e.g. PHPSESSID). It should contain only alphanumeric characters; it should be short and descriptive (i.e. for users with enabled cookie warnings). If name is specified, the name of the current session is changed to its value.

Warning

The session name can't consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.

Return Values

Returns the name of the current session. If name is given and function updates the session name, name of the old session is returned.

Examples

Example #1 session_name() example


<?php

/* set the session name to WebsiteID */

$previous_name = session_name("WebsiteID");

echo "The previous session name was $previous_name<br />";
?>

User Contributed Notes

Hongliang Qiang

11 years ago


This may sound no-brainer: the session_name() function will have no essential effect if you set session.auto_start to "true" in php.ini . And the obvious explanation is the session already started thus cannot be altered before the session_name() function--wherever it is in the script--is executed, same reason session_name needs to be called before session_start() as documented.

I know it is really not a big deal. But I had a quite hard time before figuring this out, and hope it might be helpful to someone like me.

php at wiz dot cx

7 years ago


if you try to name a php session "example.com" it gets converted to "example_com" and everything breaks.

don't use a period in your session name.

relsqui at chiliahedron dot com

7 years ago


Remember, kids--you MUST use session_name() first if you want to use session_set_cookie_params() to, say, change the session timeout. Otherwise it won't work, won't give any error, and nothing in the documentation (that I've seen, anyway) will explain why.

Thanks to brandan of bildungsroman.com who left a note under session_set_cookie_params() explaining this or I'd probably still be throwing my hands up about it.

Joseph Dalrymple

5 years ago


For those wondering, this function is expensive!

On a script that was executing in a consistent 0.0025 seconds, just the use of session_name("foo") shot my execution time up to ~0.09s. By simply sacrificing session_name("foo"), I sped my script up by roughly 0.09 seconds.

Victor H

7 months ago


As  Joseph Dalrymple said, adding session_name do slow down a little bit the execution time.
But, what i've observed is that it decreased the fluctuation between requests.
Requests on my script fluctuated between 0,045 and 0,022 seconds. With session_name("myapp"), it goes to 0,050 and 0,045. Not a big deal, but that's a point to note.

For those with problems setting the name, when session.auto_start is set to 1, you need to set the session.name on php.ini!

slave at codegrunt dot com