Troubleshooting.PHPSyntaxHighlight History

Hide minor edits - Show changes to output

June 28, 2008, at 14:43 UTC by Allan Odgaard - Add long explanation about using HTML for PHP files
Added lines 1-40:
**Problem:** I switched the language type to PHP and now I get wrong syntax highlight (or similar).

**Short answer:** Please switch back to using HTML as the language for your PHP files.

**Long answer:** PHP is short for _PHP Hypertext Preprocessor_, i.e. it is a preprocessor, it is **not** meant as a standalone language.

Quoting [the manual][1]:

> When PHP parses a file, it looks for opening and
> closing tags, which tell PHP to start and stop
> interpreting the code between them. Parsing in this
> manner allows php to be embedded in all sorts of
> different documents, as everything outside of a pair
> of opening and closing tags is ignored by the PHP
> parser. Most of the time you will see php embedded in
> HTML documents […]

So a document like the following **is not PHP**:

$var i = 42;

You **must** enclose that code in `<?php … ?>`. Even when you have a document like the following:

<?php include '' ?>

The `` include file **is still HTML**, again [quoting the PHP manual][2]:

> When a file is included, parsing drops out of PHP
> mode and into HTML mode at the beginning of the
> target file, and resumes again at the end. For this
> reason, any code inside the target file which should
> be executed as PHP code must be enclosed within valid
> PHP start and end tags.

For this reason we designed the HTML grammar to handle `<?php … ?>` tags and correctly switch to PHP mode when these tags are seen, as they are mandatory, and almost always found within HTML documents (which embed PHP).

We did **not** design PHP to be used as a stand-alone language, because from the above quotes, it is **not** a standalone language. It is **always** embedded into something else, and 99% of the time, that _something else_ is HTML.