How can the "Cannot modify header information" warning be resolved in PHP?

The "Cannot modify header information" warning in PHP occurs when you try to set a header after content has already been sent to the browser. To resolve this issue, make sure that there is no output (such as HTML, whitespace, or error messages) before calling functions like header() or setcookie(). You can use output buffering to capture any output before sending headers. 

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

// Your PHP code here

ob_end_flush(); // Flush the output buffer and send headers

Keywords

header warning PHP output buffering ob_start

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