php-markdown

I need help modifying a regular expression for PHP markdown

I'm modifying PHP Markdown (a PHP parser of the markup language which is used here on Stack Overflow) trying to implement points 1, 2 and 3 described by Jeff in this blog post. I've easily done the last two, but this one is proving very difficult: Removed support for intra-word emphasis like_this_example In fact, in the "normal" mark...