He looks at a few different topics this time - date checking, making dates more user-friendly, exploding with patterns, and capturing split delimiters. Just like in the previous articles in the series, he explains in what kind of situation the expression would be used and the sample code showing how to use it (oh, and the output too).

Following on from the last part, this one is more of an intermission-a round up of regex syntax seen so far and a couple of links following feedback.

He looks at two different topics:

• A "must reads" section of resources for getting the most out of regular expressions
• A comprehensive "cheat sheet" with tips on expression delimiters, literals, pattern modifiers, character classes, quantifiers, assertions, sub-patterns, and working with the blackslash.

He jumps right in, summarizing the first part in a small section before getting back into the examples:

• Hunting for .jp(e)gs
• Escaping Meta-Characters
• Search and Replace
• preg_quote()
• preg_replace()
• Word Boundaries, Word Characters...and everything else
• Sub patterns
• Spot the XSS Hole
• eval() is evil!
• preg_replace_callback()