ob_list_handlers()

ob_list_handlers() — List all output handlers in use.

Built-in function of PHP 8.5. The manual lists it as available in PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

Signature

ob_list_handlers(): array

Parameters

This function takes no parameters.

Return value

This will return an array with the output handlers in use (if any). If output_buffering is enabled and no output_handler is set, or no callback or null was passed to ob_start(), "default output handler" is returned. Enabling output_buffering and setting an output_handler is equivalent to passing an internal (built-in) function to ob_start(). If a callable was passed to ob_start(), the fully qualified name of the callable is returned. If the callable is an object implementing __invoke(), the fully qualified name of the object's __invoke() method is returned. If the callable is a Closure, "Closure::__invoke" is returned.

Example

A runnable snippet:

// using output_buffering=On, no output_handler set var_dump(ob_list_handlers()); ob_end_flush(); // no callback or null ob_start(); var_dump(ob_list_handlers()); ob_end_flush(); // anonymous function ob_start(function($string) { return $string; }); var_dump(ob_list_handlers()); ob_end_flush(); // arrow function ob_start(fn($string) => $string); var_dump(ob_list_handlers()); ob_end_flush(); // first class callable $firstClassCallable = userDefinedFunction(...); ob_start([$firstClassCallable, '__invoke']); var_dump(ob_list_handlers()); ob_end_flush(); // internal (built-in) function ob_start('print_r'); var_dump(ob_list_handlers()); ob_end_flush(); // user-defined function function userDefinedFunction($string, $flags) { return $string; }; ob_start('userDefinedFunction'); var_dump(ob_list_handlers()); ob_end_flush(); class MyClass { public static function staticHandle($string) { return $string; } public static function handle($string) { return $string; } public function __invoke($string) { return $string; } } // class and static method ob_start(['MyClass','staticHandle']); var_dump(ob_list_handlers()); ob_end_flush(); // object and non-static method ob_start([new MyClass,'handle']); var_dump(ob_list_handlers()); ob_end_flush(); // invokable object ob_start(new MyClass); var_dump(ob_list_handlers()); ob_end_flush();

Output:

array(1) { [0]=> string(22) "default output handler" } array(1) { [0]=> string(22) "default output handler" } array(1) { [0]=> string(7) "print_r" } array(1) { [0]=> string(19) "userDefinedFunction" } array(1) { [0]=> string(17) "Closure::__invoke" } array(1) { [0]=> string(17) "Closure::__invoke" } array(1) { [0]=> string(17) "Closure::__invoke" } array(1) { [0]=> string(21) "MyClass::staticHandle" } array(1) { [0]=> string(15) "MyClass::handle" } array(1) { [0]=> string(17) "MyClass::__invoke" }

See also

ob_end_clean(), ob_end_flush(), ob_get_flush(), ob_start()

All PHP 8.5 built-in functions

Reference card built from the PHP manual page ob_list_handlers() (PHP documentation, CC BY 3.0). The page is generated from the manual, so the wording of the parameter and return value text follows php.net.