How can the error "Warning: Cannot modify header information - headers already sent" be resolved when trying to set a cookie in PHP?

When this error occurs, it means that PHP is trying to set a cookie after headers have already been sent to the browser. To resolve this issue, make sure that there is no whitespace or any output (like echo or print statements) before the setcookie() function. You can also use ob_start() and ob_end_flush() functions to buffer the output and prevent headers from being sent prematurely. 

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

// Your PHP code here

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

ob_end_flush(); // Flush output buffer
?>

Keywords

PHP headers cookies output buffering ob_start

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