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    header_register_callback

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

    header_register_callback — Call a header function

    Опис

    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.

    Параметри

    callback

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

    Значення, що повертаються

    Повертає true у разі успіху або false в разі помилки.

    Приклади

    Приклад #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";
    ?>

    Поданий вище приклад виведе щось схоже на:

    Content-Type: text/plain

a

    Примітки

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

    Зауваження:

    Заголовки будуть доступні та виводитимуться, тільки якщо використовується SAPI, який їх підтримує.

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    User Contributed Notes 1 note

    up
    12
    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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