Ken Guest, in a response to another post from a different blogger, has posted some of his own validation replacements for the regular expression method the other blogger chose.

I've noticed that Richard Heyes, who professes himself to be a php guru, deleted my comment on his "Some common regular expressions" posting which simply pointed out his expressions didn't quite do the job and suggested a few PEAR packages that should be used instead of the expressions that he proffered

His examples have the benefit of what he calls "defense in depth" - the functionality to catch a bit more than just a regular expression can alone. His examples include PEAR_Validate for email addresses, Net_CheckIP2 for IP addresses and the Validate_UK package for the sort code and telephone numbers.

Eirik Hoem has pointed out an online tool a coworker shared with him to work with regular expressions for multiple languages.

A coworker of mine has been working on a ajax enabled regex tool which lets you evaluate regex expressions in several languages (including PHP PCRE and PHP POSIX) with instant results.

The tool lets you put in the string you want to match again and the pattern you want to match with. The results are automatically populated below it, making it easy to fine-tune your expression to only what you want.

On the Developer Tutorials blog, Akash Mehta offers some suggestions of resources and methods for learning how to use regular expressions in your PHP applications.

When it comes to quickly dealing with large blocks of data, batch processing operations or screen scraping, regular expressions are often the most effective solution. There's just one problem, though - learning them can be as hard as learning a new language altogether. Here's how to get off to a flying start.

He points you first in the direction of the preg_* functions then towards a few examples (like with mod_rewrite) and tools to help you understand how things match, like the regex tested extension for firefox and the regular expression cheat sheet on ILoveJackDaniels.com.

The IBM developerWorks website has posted the first part of a series they've created to help PHP developers become more informed about what regular expressions are and how they can harness their power for their applications.

Pattern matching is such a common chore for software that a special shorthand â€" regular expressions â€" has evolved to make light work of the task. Learn how to use this shorthand in your code here in Part 1 of this "Mastering regular expressions in PHP" series.

In this first part of the series, they look at the basics - the idea behind regular expressions, some of the common operators, the PHP functions to use them and example of how to use them to match/split out strings and capture just the data you need from the given input.

Gareth Heyes has posted another challenge to his blog - this time it involves using a regular expression to convert the inputted string into the output he's given.

After the success of my "a bit of fun" challenge, a few people asked for some more challenges. So I was answering a question on a mailing list that I'm a member of and I thought it would be a good topic for a little challenge and help sharpen everyone's regular expression skills.

This time, his challenge involves taking the input, rail start/end locations from an array and, via the PHP script given (no regular expression in it, of course) make the output, a sort of JSON formatted message. It's already been answered, but if you want to, try it yourself first then read the answer below the post.

On his web development blog, Joey has posted a new list of eight handy regular expressions you can use in your code for common validations.

Here are eight examples of practical PHP regular expressions and techniques that I've used over the past few years using Perl Compatible Regular Expressions. This guide goes over the eight different validation techniques and describes briefly how they work. Usernames, telephone numbers, email addresses, and more.

Each of the regular expressions comes complete with an explanation of what it is and the kinds of strings it's looking for. Comments on the post have helped even more, finding places where they might break or not catch all possibilities.

On the Dotvoid.com blog today, there's a new post that shares some handy code to parse out information from the incoming user agent string for the visitors for your site.

Recently I experimented a bit with an Apache log file analyzer written in PHP. It's not all that difficult were it not for trying to parse the browser, or user agent, string. [...] For my purposes I don't care much for the operating system details. This is the result so far. I'm still not very satisfied but I thought maybe other people might be interested and maybe help out.

He provides the code in the format of an encapsulated PHP function that returns the product they're using, the version number of the browser and other various comments.

The Zend Developer Zone has posted a bit of info of special interest to those out there working with PHP and MySQL. Prentice Hall has posted a sample chapter of their "PHP and MySQL By Example" book for public consumption.

Most developers I know of either love or hate Regular Expressions, me personally, I hate them. Yes, they do the job and usually do it elegantly but it's hard to find a more arcane sub-language than regex.

Obviously, the sample chapter talks about regular expressions - specifically what they are, what functions in PHP use them, their use, and enough examples to keep you busy for a long time.

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Though not specifically related to PHP, I wanted to share a helpful tip that Tiffany Brown has posted to her blog today - a nice, compact regular expression to handle the matching of email addresses.

A few weeks ago, I posted a regular expression pattern < href="http://tiffanybbrown.com/2006/11/09/a-pattern-for-matching-e-mail-addresses/">for matching e-mail addresses. Below is a more refined version:

Not only does it match the traditional email address formats, but it also will match addresses with periods in the name, British domains, and new TLDs like '.travel' or '.museum'.

Harry Fuecks brings the next part of his "Joy of Regular Expressions" series to the SitePoint PHP Blog today with part four, building on the previous how-tos: part one, part two, and part three.

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).