Delving into the Distinction between session_unset() and session_destroy() in PHP

When working with PHP sessions, developers often must choose between the functions session_unset() and session_destroy(). Despite sounding similar, these functions exhibit notable differences.

Functionality Differences

While both functions affect session variables, their impact on session data differs. session_unset() clears the $_SESSION variable, akin to manually assigning it an empty array. This action purely affects the local $_SESSION instance, leaving session data in the storage unaffected.

In contrast, session_destroy() eliminates session data from the storage. Whether in a file system, database, or other storage, it erases all stored session information.

Session Destruction

Neither session_unset() nor session_destroy() eliminates the session itself or its associated cookie. If explicit session destruction is desired, PHP provides another function: session_start(). By invoking this function with no arguments, you can effectively destroy the current session.

Cookie Management

Both session_unset() and session_destroy() do not impact the session cookie stored on the client's device. Therefore, for complete session termination, additional measures are required, such as deleting or expiring the cookie.