How can PHP developers prevent output before using header("Location: ...") for redirection?

When using header("Location: ...") for redirection in PHP, developers should ensure that no output is sent to the browser before this header function is called. This is because headers must be sent before any actual output is sent to the browser. To prevent any output before redirection, developers can use output buffering to capture any output and prevent it from being sent to the browser until the redirection is complete. 

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

// Your PHP code here

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

header("Location: your_redirect_url_here"); // Perform the redirection
exit(); // Make sure to exit after setting the header
?>

Keywords

output buffering ob_start ob_end_flush headers_sent exit

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