(PHP 5 >= 5.4.0, PHP 7)
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.
callbackFunction called just before the headers are sent. It gets no parameters and the return value is ignored.
Retorna TRUE em caso de sucesso ou FALSE em caso de falha.
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 irá imprimir algo similar à:
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:
Headers só serão acessíveis e retornados quando a SAPI que os suporta estiver em uso.