How can the use of setcookie() and header() functions in PHP code be affected by the content that is output before them?

When using the setcookie() and header() functions in PHP, it is important to ensure that no content has been output to the browser before calling these functions. Outputting content before these functions can result in headers already being sent to the browser, causing the functions to fail. To avoid this issue, make sure to call these functions before any HTML, text, or whitespace is output. 

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

// Code logic here

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

// Set header
header("Location: new_page.php");

ob_end_flush(); // Flush output buffer
?>

Keywords

setcookie header output buffering headers already sent PHP output buffer

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