Performs the gc operation on PHP session state, settings or persistence for the active request.
Before using it, identify which data, connection or runtime state the operation reads or changes. This avoids examples that appear to work but apply to a different context.
What Is session_gc() in PHP?
Performs the gc operation on PHP session state, settings or persistence for the active request.
Syntax:
<?php
// Signature for reference only
session_gc() : int|false
Parameters and Return Value
This operation does not accept any arguments.
The declared return type is int|false.
Example 1: Basic Usage
<?php
session_start();
var_dump(session_gc());Performs the gc operation on PHP session state, settings or persistence for the active request.
Example 2: Another Case
<?php
session_start();
$removedSessions = session_gc();
var_dump($removedSessions);The second sample illustrates a different way to inspect or handle this operation. Configure the underlying session, socket, key material or connection first.
Practical Example
<?php
session_start();
$collected = session_gc();
echo $collected === false ? "GC unavailable" : "Removed: " . $collected;The practical example is a teaching scenario. Change sample configuration and credentials before using a similar design in an application.
Important Behavior and Edge Cases
- Call session configuration functions before starting a session or sending headers; protect identifiers from exposure.
- Relevant PHP environment: session. Ensure the required extension and operating-system capabilities are present.
- Check results and release resources where necessary; successful syntax alone does not guarantee a successful operation.
Comparison With Related Functions
| Option | When to Use It |
|---|---|
session_gc | Performs the gc operation on PHP session state, settings or persistence for the active request. |
session_start | Use this related operation for its different responsibilities; do not assume identical inputs or return values. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Starting the session after response output | Configure cookie flags and session handling before sending body bytes. |
| Assuming session_destroy() removes the browser cookie | Clear session data and expire the cookie using matching scope settings. |
| Keeping the same session ID after authentication | Rotate the identifier when privileges change and use strict mode. |
Key Takeaways
- Performs the gc operation on PHP session state, settings or persistence for the active request.
- Call session configuration functions before starting a session or sending headers; protect identifiers from exposure.
- Validate inputs and handle failure conditions before integrating this operation into a production workflow.
Performs the gc operation on PHP session state, settings or persistence for the active request. Use the appropriate runtime and treat any environment-dependent output as an example, not a guaranteed result.