How can PHP developers prevent or troubleshoot issues related to headers being sent before using the header() function?

When headers are sent before using the header() function in PHP, it can cause errors such as "Headers already sent" or prevent the headers from being set correctly. To prevent this issue, developers should ensure that no output is sent to the browser before calling the header() function, including whitespace, HTML, or PHP errors. To troubleshoot, developers can use output buffering to capture any output before sending headers. 

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

// Your PHP code here

ob_end_clean(); // Clean the output buffer without sending it

// Now you can safely use the header() function
header("Location: https://www.example.com");
?>

Keywords

headers_sent output buffering ob_start ob_end_flush error_reporting

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