headers_sent

symfony/var-dumper

Supported Versions: PHP 4, PHP 5, PHP 7, PHP 8

Checks if or where headers have been sent

<?php headers_sent(string &$filename = null, int &$line = null): bool

<?php     function dd(...$vars)

    {

        if (!in_array(\PHP_SAPI, ['cli', 'phpdbg'], true) && !headers_sent()) {

            header('HTTP/1.1 500 Internal Server Error');

        }

Resources/functions/dump.php