如何将某些内容添加到PHP输出缓冲区的开头？

Question

How do you append something to the beginning of the output buffer?

For example, say you have the following code:

ob_start();

echo '<p>Start of page.</p>';
echo '<p>Middle of page.</p>';
echo '<p>End of page</p>';

Before flushing the contents to the browser, how can I append something so that it appears before <p>Start of page.</p> when the page loads?

It sounds simple enough, like moving the pointer to the beginning of an array, but I couldn't find how to do it with the output buffer.

Answer 1

** PHP 5.3 **

ob_start(function($output) {
    $output = '<p>Prepended</p>'.$output;
    return $output;
});

echo '<p>Start of page.</p>';
echo '<p>Middle of page.</p>';
echo '<p>End of page</p>';

** PHP < 5.3 **

function prependOutput($output) {
    $output = '<p>Appended</p>'.$output;
    return $output;
}

ob_start('prependOutput');

echo '<p>Start of page.</p>';
echo '<p>Middle of page.</p>';
echo '<p>End of page</p>';