(PHP 5 >= 5.4.0, PHP 7, PHP 8)
header_register_callback — Call a header function
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.
callback
Function called just before the headers are sent. It gets no parameters and the return value is ignored.
Exemplo #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";
?>
O exemplo acima produzirá algo semelhante a:
Content-Type: text/plain a
header_register_callback() is executed just as the headers are about to be sent out, so any output from this function can break output.
Nota:
Os cabeçalhos só serão acessíveis e enviados quando uma SAPI que os suporta estiver em uso.