How can the placement of session_start() in a PHP script affect its functionality?

Placing the session_start() function at the beginning of a PHP script is crucial for initializing session data before any output is sent to the browser. If session_start() is placed after any output (like HTML, whitespace, or even a newline), it will result in a "headers already sent" error. To avoid this issue, always ensure that session_start() is the first thing in your PHP script, before any other code or output. 

<?php
session_start();

// Other PHP code here
?>
<!DOCTYPE html>
<html>
<head>
    <title>Session Example</title>
</head>
<body>
    <!-- HTML content here -->
</body>
</html>

Keywords

session_start PHP script functionality placement affect

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