session_id
(PHP 4, PHP 5, PHP 7, PHP 8)
session_id — Get and/or set the current session id
Description
$id = null): string|falsesession_id() is used to get or set the session id for the current session.
The constant SID can also be used to
retrieve the current name and session id as a string suitable for
adding to URLs. See also Session
handling.
Parameters
-
id -
If
idis specified and notnull, it will replace the current session id. session_id() needs to be called before session_start() for that purpose. Depending on the session handler, not all characters are allowed within the session id. For example, the file session handler only allows characters in the rangea-z A-Z 0-9 , (comma) and - (minus)!Note: When using session cookies, specifying an
idfor session_id() will always send a new cookie when session_start() is called, regardless if the current session id is identical to the one being set.
Return Values
session_id() returns the session id for the current
session or the empty string ("") if there is no current
session (no current session id exists).
On failure, false is returned.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
id is nullable now.
|
See Also
- session_regenerate_id() - Update the current session id with a newly generated one
- session_start() - Start new or resume existing session
- session_set_save_handler() - Sets user-level session storage functions
- session.save_handler
