header_register_callback

(PHP 5 >= 5.4.0, PHP 7, PHP 8)

header_register_callback — Call a header function

Beschreibung

header_register_callback(callable $callback): bool

Registers a function that will be called when PHP starts sending output.

The callback is executed just after PHP prepares all headers to be sent, and before any other output is sent, creating a window to manipulate the outgoing headers before being sent.

Parameter-Liste

callback: Function called just before the headers are sent. It gets no parameters and the return value is ignored.

Rückgabewerte

Gibt bei Erfolg true zurück. Bei einem Fehler wird false zurückgegeben.

Beispiele

Beispiel #1 header_register_callback() example

<?php

header('Content-Type: text/plain');
header('X-Test: foo');

function foo() {
 foreach (headers_list() as $header) {
   if (strpos($header, 'X-Powered-By:') !== false) {
     header_remove('X-Powered-By');
   }
   header_remove('X-Test');
 }
}

$result = header_register_callback('foo');
echo "a";
?>

Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:

Content-Type: text/plain

a

Anmerkungen

header_register_callback() is executed just as the headers are about to be sent out, so any output from this function can break output.

Hinweis:
Header sind nur dann zugänglich und werden nur dann gesendet, wenn die genutzte SAPI sie unterstützt.

Siehe auch

headers_list() - Liefert eine Liste der gesendeten (oder zum Senden vorbereiteten) Antwort-Header
header_remove() - Remove previously set headers
header() - Sendet einen HTTP-Header in Rohform

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User Contributed Notes 1 note

down

matt@kafene ¶

11 years ago

Note that this function only registers a single callback as of php 5.4. The most recent callback set is the one that will be executed, they will not be executed in order like with register_shutdown_function(), just overwritten.

Here is my test:

<?php

$i = $j = 0;
header_register_callback(function() use(&$i){ $i+=2; });
header_register_callback(function() use(&$i){ $i+=3; });
register_shutdown_function(function() use(&$j){ $j+=2; });
register_shutdown_function(function() use(&$j){ $j+=3; });
register_shutdown_function(function() use(&$j){ var_dump($j); });
while(!headers_sent()) { echo "<!-- ... flushing ... -->"; }
var_dump(headers_sent(), $i);
exit;

?>

Results:

headers_sent() - true
$i = 3
$j = 5

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