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Using highlight_file with header() to Output Correct Content-Type Header Information

M66 2025-07-08 
<span class="hljs-meta"><?php
// This section contains PHP example code unrelated to the main content
echo "The following is the main content:";
?>
<hr>
<h2>Using highlight_file with header() to Output Correct Content-Type Header Information</h2>
<p>When using the built-in PHP <code>highlight_file<span>()

In this code:

  1. header() must be called before any output, otherwise a "Headers already sent" error will occur.

  2. highlight_file() will highlight the PHP code of the target file and output it in HTML format.

  3. Using __FILE__ as the argument means highlighting the code of the current file. This is useful for debugging or educational demonstrations.

Additionally, if you want to highlight another file, just replace __FILE__ with the specific path, but ensure the target file is within the access permissions and does not expose sensitive information.

Tips

  • If you're using this for teaching or code demonstration websites, it's recommended to add appropriate styles or wrap the code in an HTML template to improve readability and user experience.

  • Avoid using highlight_file() on files containing sensitive data, especially in a production environment.

By correctly setting the Content-Type, highlight_file() can be safely and clearly used to display PHP source code, making it a valuable tool for lightweight teaching and debugging scenarios.

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