How can headers already sent errors be resolved when setting cookies in PHP?

Headers already sent errors occur in PHP when there is output sent to the browser before setting headers, such as when setting cookies. To resolve this issue, ensure that there is no output (including whitespace) before setting headers. One common solution is to place the session_start() function at the beginning of the PHP script before any output. 

<?php
ob_start(); // Start output buffering
session_start(); // Start the session

// Set a cookie
setcookie("cookie_name", "cookie_value", time() + 3600, '/');

ob_end_flush(); // Flush output buffer
?>

Keywords

headers_sent setcookie ob_start output buffering PHP

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