How can separating PHP logic and HTML output help prevent the error "cannot modify header information - headers already sent by" in PHP?

When PHP logic and HTML output are mixed together, it can lead to premature output being sent to the browser before headers are set, causing the "cannot modify header information - headers already sent by" error. To prevent this error, it is important to separate PHP logic from HTML output by using PHP's output buffering functions like ob_start() and ob_end_flush(). 

<?php
ob_start();
// PHP logic here

// HTML output here

ob_end_flush();
?>

Keywords

PHP logic separation HTML output header information error prevention

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