What are the common reasons for headers already sent error in PHP and how can they be prevented in the code?

The common reasons for "headers already sent" error in PHP are outputting data before calling the header() function, including whitespace or HTML tags before <?php or after ?>, or sending HTTP headers after outputting content. To prevent this error, make sure to place the header() function before any output is sent to the browser, avoid using closing PHP tags at the end of files, and ensure that no whitespace is present before the opening <?php tag. 

&lt;?php
ob_start(); // Start output buffering

// Place header() function before any output
header(&#039;Location: https://www.example.com&#039;);

ob_end_flush(); // Flush output buffer
exit;
?&gt;

Keywords

headers already sent error PHP prevention

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