PHP | header_register_callback() Function

PHP header_register_callback() Function

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP header_register_callback() Function.

The built-in PHP header_register_callback() function registers the function that will be called when PHP start sending output.


Following below is the syntax to use this function -

bool header_register_callback ( callable $callback )

Parameter Details

Sr.NoParameters & Description


It called before the headers are sent.

Return Value

This PHP function returns true on success and false on failure.


Try out the following example below -

   header('Content-Type: text/plain');
   header('X-Test: f1');
   function f1() {
      foreach (headers_list() as $header) {
         if (strpos($header, 'X-Powered-By:') !== false) {
   $result = header_register_callback('f1');
   echo "webdesigntutorialz";


When the above code is executed, it will produce the following result below -


Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we will study about the PHP header_remove() Function.

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