session_unset

Function name: session_unset()

Function function: session_unset() function is used to release the values ​​of all variables in the current session.

Parameter description: No parameters.

Return value: This function does not return value.

Sample code:

 <?php // 开启会话session_start(); // 设置会话变量$_SESSION['username'] = 'John'; $_SESSION['age'] = 25; // 输出会话变量的值echo '用户名：' . $_SESSION['username'] . '<br>'; echo '年龄：' . $_SESSION['age'] . '<br>'; // 清空会话变量session_unset(); // 输出会话变量的值，应该为空echo '用户名：' . $_SESSION['username'] . '<br>'; echo '年龄：' . $_SESSION['age'] . '<br>'; ?>

Version of usage: This function is available in PHP 4, PHP 5, and PHP 7.

Notes:

• The session_unset() function will only clear the variable values ​​in the current session and will not destroy the session itself.
• If you need to destroy the entire session, you can use the session_destroy() function.
• After calling the session_unset() function, you can check whether the session variable exists through the isset() function.
• After calling the session_unset() function, the value of the session variable will be set to NULL.
• After calling the session_unset() function, the session_register_shutdown() function can be used to trigger the closing and storage of the session.
• After calling the session_unset() function, you can save the session data and close the session through the session_commit() function.
• Normally, it is recommended to call the session_unset() function before the script ends to free the value of the session variable.