How can one prevent output before the header() function in PHP to avoid errors?

To prevent output before the header() function in PHP and avoid errors, you should ensure that no content is sent to the browser before calling the header() function. This can be achieved by placing the header() function at the very beginning of your PHP script, before any HTML tags, whitespace, or echo/print statements. 

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

// Place header() function at the beginning
header("Location: https://www.example.com");
exit();

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

Keywords

output buffering ob_start header function headers already sent PHP errors

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