Question

I want to encode (htmlentities) or disable all tags except for <a> tags.

How can I achieve this?

Answer 1

After using HTML entities, convert the links back using a RegExp:

preg_replace('/&lt;(\/?a(?:|\s[\S\s]+?))&gt;/i', '<$1>', $string);

If you want other tags to be removed, use:

strip_tags($string, '<a>');