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Accepted
Sonia Toledo
Asked: 2022-05-12 12:50:25 +0800 CST 2022-05-12 12:50:25 +0800 CST

Headers are sent without problems even after sending an output

  • 772

In this I would like to achieve the opposite, there are no errors, I want to generate them. I'm studying the use of PHP's ob_* functions. I found this code to understand the concepts, and it is supposed to throw an error, since I understand that once an output is sent, the headers can no longer be modified, or set the sessions or cookies. Can someone explain to me why everything flows smoothly?

  <?php
    //ob_start();

echo '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">';

?>
<html>

<head>
    <title>Página procesada con buffer de salida</title>
</head>

<body>
    Esta es mi página!!!
</body>

</html>
<?php

setcookie("nombre", "john");
//ob_end_flush(); 
?>
php

1 Answers

  1. Best Answer

    Surely in your server you have activated a buffer or output control ; the behavior can be modified at php.inior at runtime, depending on the characteristics of the server; remember that shared servers rarely allow these changes.

    There are two important variables:

    • output_buffering : Although the manual mentions that the default value is zero, most of the time it has the number of bytes that should be accumulated in the buffer before sending it to the browser (or standard output). On my local server, without having modified, it has 4096.
    • implicit_flush : Defaults to offand, when set to on, all output is immediately sent to the browser (or stdout).

    Edit the file php.inicorresponding to your version of PHP (and restart the server) or set at runtime with ini_set('variable', 'new value'); , setting output_bufferingto zero and implicit_flushto on.

    In theory, this should send any output immediately and your script should show errors, of course, as long as you have that option enabled as well; otherwise, check the documentation to configure the errors you want to show.

    Important remark:

    It's a very good idea to do these tests for debugging purposes, but remember to return to the original values ​​when your project is in production, otherwise there may be performance issues.

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