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    header_register_callback

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

    header_register_callback — Call a header function

    Descrizione

    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.

    Elenco dei parametri

    callback

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

    Valori restituiti

    Restituisce true in caso di successo, false in caso di fallimento.

    Esempi

    Example #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";
    ?>

    Il precedente esempio visualizzerà qualcosa simile a:

    Content-Type: text/plain

a

    Note

    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:

    Gli header sono accessibili (e emessi nell'output) quando è in uso un SAPI che li supporta.

    Vedere anche:

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    User Contributed Notes 1 note

    up
    6
    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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