How can headers affect the functionality of setcookie() in PHP?

Headers can affect the functionality of setcookie() in PHP because setcookie() must be called before any output is sent to the browser. If headers are already sent (due to HTML content or whitespace before the setcookie() function), the cookie cannot be set successfully. To solve this issue, you can use the ob_start() function to buffer the output, allowing you to set cookies even after output has started. 

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

// Your PHP code here

setcookie("cookie_name", "cookie_value", time() + 3600, "/");
// Set the cookie after any output

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

Keywords

headers setcookie() functionality PHP cookies

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