Regex is a really powerful tool, but sometimes I wonder just how well people actually understand it as the vast majority of people (myself included) seem to be self taught in the syntax - only learning the bits they need as and when they need it.

The problem is, regular expressions is packed full of counter intuitive idiosyncrasies which make perfect sense once they're explained, but are far from obvious. Take this for example:

    s/(^\s+|\s+$)//g

is slower than running two separate regex, like so:

    s/^\s+//;
    s/\s+$//;

So it does make me wonder the number of bugs that have been introduced to software by bad regex.