highlighting php source code in WordPress

March 11th, 2005. Tagged: WordPress

The source code highlighting was probably the first feature I was missing in WordPress. I briefly googled my options and decided it would be quicker to add the missing feature myself, since it looked pretty straightforward.

So what I did:
1. I added a hilite() function in functions-formatting.php

function hilite($text)


    $text = str_replace('<? php', '<?php', $text);

    return preg_replace_callback(




                 'return highlight_string($matches[0], true); '





The first line of the function is pretty curious, I agree. I needed it because I noticed that WP is adding a space between < and ? before saving to the database.

2. I added call to the new function in default-filters.php

add_filter('the_content', 'hilite');

... just before this line

add_filter('the_content', 'wptexturize');

And it worked! Only that the highlighting itself for some reason is using the HTML font tag (God forbid!), but I believe that's server setup.

I added the filter to one more place in default-filters.php, in order to highlight source code when listing excerpts, for example category listing on an archive listing. So default-filters.php looks more like:
add_filter('the_content', 'hilite');
add_filter('the_content', 'wptexturize');
add_filter('the_excerpt', 'hilite');
add_filter('the_excerpt', 'wptexturize');

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5 Responses

  1. Nice simple little method thanks, after looking at the PHP manual is appears as though font tags are used in PHP 4 and span tags in PHP 5:

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