Sometimes, it's just not enough to sit and try to teach theory about something in programming - it's better to just jump right in and take things as they come. That's what Harry Fuecks thinks, at least in his latest post on the SitePoint PHP Blog - a look at the "Joy of Regular Expressions".

He does go over a bit of the theory and why they are so invaluable, but it's a short section before he gets to the heart of the article - working with regular expressions for:

• positive matching
• matching all instances in a given string
• finding an exact match
• matching the start of a string
• validation of the contents of a string
• checking the length of a string

There's simple examples included for each of the items to help you get an idea of how they'd work.