在其他文本中使用preg_replace（）作为后缀和后缀

Question

I've been trying to make a mini markup parser similar to Markdown in PHP. The input looks like this:

Some text **that is bold!** and some other text

into

Some text <b>that is bold!</b> and some other text

I've found countless resources on how to replace a chunk of text with another, but only one that actually replaces suffix and postfix: this answer. After messing around with it a bit it looks like this:

$s=preg_quote("**");

$in = preg_replace(
    array('%'.$s.'-%', '%-%', '%'.$s.'%'), 
    array('<b>','_','</b>'),
    $in);

Earlier attempts are equally clumsy. It's obvious I don't really get regex or that engine's syntax so I'm at a loss. The alternative is to hack the string into pieces and add/remove what I need, but regex seems much more elegant. Any ideas?

---

Fix: Earlier I wrote $s=preg_quote($s) by mistake, corrected to $s=preg_quote("**")

Answer 1

You should use a basic '\*\*(.+?)\*\*' regex.

$s = preg_replace(
    '/\*\*(.+?)\*\*/isU',
    '<b>$1</b>',
    $s);