How can PHP developers ensure that they do not encounter the "headers already sent" error when using the header() function?

When using the header() function in PHP, developers can ensure they do not encounter the "headers already sent" error by making sure that no output is sent to the browser before calling the header() function. This error occurs when PHP tries to send HTTP headers after content has already been sent to the browser. To prevent this, developers should place the header() function before any output, including any whitespace or HTML tags. 

<?php
ob_start(); // Start output buffering
header('Location: https://www.example.com'); // Redirect header
ob_end_flush(); // Flush output buffer
exit; // Terminate script execution
?>

Keywords

header function output buffering ob_start ob_end_flush error_reporting

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