What are best practices for preventing the "headers already sent" error in PHP scripts?

The "headers already sent" error in PHP scripts occurs when output is sent to the browser before headers are set, which can prevent headers like cookies or redirects from being sent. To prevent this error, ensure that no output is sent before calling functions like header() or setcookie(). One common practice is to place all header-related functions at the beginning of the script before any HTML or whitespace. 

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

// Place header-related functions at the beginning of the script
header('Content-Type: text/html');

// Rest of the PHP script goes here

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

Keywords

output buffering ob_start header error_reporting ob_end_clean

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