On PHPBuilder.com today, there's a new tutorial covering one of the more powerful things you can use in PHP to manipulate strings (and similar data) - regular expressions.

A regular expression is a specially formatted pattern that can be used to find instances of one string in another. Several programming languages including Visual Basic, Perl, JavaScript and PHP support regular expressions, and hopefully by the end of this primer you should be able to implement some basic regular expression functionality into your PHP pages.

They start with the basics of what they are and take a brief look at the two different types of functions that PHP has to offer for their use (the ereg* group and the preg* group).