PHP Replace, But Alternate Replace String
markdown, php, replace
Solution
Personally, I'd loop through each occurrence of `*` or `\` with a counter, and replace the character with the appropriate HTML tag based on the count (for example, if the count is even and you hit an asterisk, replace it with `<em>`, if it's odd then replace it with `</em>`, etc).
But if you're sure that you only need to support a couple simple kinds of markup, then a regular expression for each might be the easiest solution. Something like this for asterisks, for example (untested):
preg_replace('/\*([^*]+)\*/', '<em>\\1</em>', $text);
And something similar for backslashes.
Problem
Okay, here's what I'm trying to do: I'm trying to use PHP to develop what's essentially a tiny subset of a markdown implementation, not worth using a full markdown class. I need essentially do a str_replace, but alternate the replace string for every occurrence of the needle, so as to handle the opening and closing HTML tags. For example, italics are a pair of asterisks like *this*, and code blocks are surrounded by backticks like `this`. I need to replace the first occurrence of a pair of the characters with the opening HTML tag corresponding, and the second with the closing tag. Any ideas on how to do this? I figured some sort of regular expression would be involved...