How can the issue of "Cannot add header information - headers already sent" be resolved in PHP when trying to implement a header redirect?

The issue of "Cannot add header information - headers already sent" in PHP occurs when there is output (such as whitespace or HTML) sent before the header() function is called to perform a redirect. To resolve this issue, make sure there is no output sent before the header() function is called, and use ob_start() to buffer the output if necessary. 

<?php
ob_start(); // start output buffering

// your PHP code here

header('Location: newpage.php'); // perform the header redirect

ob_end_flush(); // flush the output buffer
?>

Keywords

header redirect ob_start ob_end_flush output buffering

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