How can developers effectively troubleshoot and resolve the issue of headers already being sent in PHP?

When headers are already sent in PHP, it means that some content has already been output to the browser before header functions like `header()` or `setcookie()` are called. To resolve this issue, developers can ensure that no content is output before sending headers by checking for any whitespace or HTML tags outside of PHP tags in their files. 

<?php
ob_start(); // Start output buffering
// Your PHP code here

// Check for any whitespace or HTML tags before sending headers
if (headers_sent()) {
    // Handle the error or redirect to another page
    exit;
}

// Send headers
header('Location: index.php');
ob_end_flush(); // Flush output buffer
?>

Keywords

output buffering ob_start ob_clean header error_reporting

Related Questions