session_id

Function name: session_id()

Applicable version: PHP 4, PHP 5, PHP 7

Function description: The session_id() function is used to obtain or set the session ID of the current session.

usage:

1. Get the session ID of the current session:

    $sessionId = session_id(); echo "当前会话的session ID为：" . $sessionId;

2. Set the session ID of the current session:

    session_id("custom_session_id"); session_start(); echo "当前会话的session ID已设置为custom_session_id";

Notes:

• Before calling the session_id() function, the session_start() function must be called to start the session.
• If you need to set the session ID, it must be set before calling the session_start() function.
• The session ID must be unique and comply with the specifications of the session ID (usually composed of letters, numbers, and special characters).
• If the session ID is not set, a unique session ID will be automatically generated.

Example explanation:

• The first example demonstrates how to get the session ID of the current session and print it out.
• The second example demonstrates how to set the session ID of the current session to "custom_session_id" and print it out after calling the session_start() function.

Please note that the session_id() function is only used to obtain or set the session ID of the current session and does not involve actual session data operations. To manipulate session data, you can use other session-related functions, such as $_SESSION array.