How can one prevent the issue of headers already being sent in PHP?

The issue of "headers already sent" in PHP occurs when there is output sent to the browser before headers are set using functions like `header()` or `setcookie()`. To prevent this issue, make sure that no output is sent before setting headers, including any whitespace or HTML tags. One way to solve this is to move all header-related functions to the very beginning of the script before any output is generated. 

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

// Set headers before any output
header('Content-Type: text/html');

// Rest of your PHP code here

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

Keywords

output buffering ob_start ob_end_flush header headers_sent

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