How can the order of code execution impact the effectiveness of PHP header redirects?

The order of code execution can impact the effectiveness of PHP header redirects because headers must be sent before any actual output is sent to the browser. If there is any output (such as HTML or whitespace) before the header redirect is called, it will result in a "headers already sent" error. To solve this issue, make sure to place the header redirect code at the very beginning of your PHP file, before any other code or output. 

<?php
// Place this code at the very beginning of your PHP file
ob_start();
header('Location: http://www.example.com');
exit();
?>

Keywords

PHP header redirects code execution effectiveness output buffering

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