PHP ob_list_handlers() Function

The PHP ob_list_handlers() function returns an array with the names of the callback functions that were passed into the ob_start() function of the topmost output buffer.

If output_buffering is enabled or an anonymous function was used with ob_start(), this function returns "default output handler".

Syntax

ob_list_handlers()

Parameters

No parameter is required.

Return Value

Returns an array with the output handlers in use (if any). If output_buffering is enabled or an anonymous function was used with ob_start(), it returns "default output handler".

Example: ob_list_handlers() example

The example below shows the usage of ob_list_handlers() function.

<?php
//using ob_gzhandler() function
ob_start("ob_gzhandler");
print_r(ob_list_handlers());
ob_end_flush();

//using anonymous functions
ob_start(function($string) {return $string;});
print_r(ob_list_handlers());
ob_end_flush();
?>

The output of the above code will be:

Array
(
    [0] => ob_gzhandler
)
Array
(
    [0] => Closure::__invoke
)

Example: using output_buffering=On

Consider one more example where this function is used with output_buffering=On. Please note that the output_buffering=On can be set in php.ini.

<?php
//using output_buffering=On
print_r(ob_list_handlers());
ob_end_flush();
?>

The output of the above code will be:

Array
(
    [0] => default output handler
)