If you are a programmer, then you must have encountered regular expressions sometime back in your carrier. If you are good at regular expressions, then hats off to you. Otherwise there are some tools which can make your life easy.
There is one online and one offline tool that I often use for regular expression purpose which I like to share with you today.
1. Regular Expression Online Tool
For PHP, it supports both PCRE (Perl Compatible Regular Expression) and POSIX library. There is no support for other languages but I that only means you may not be able to generate code for those. You can still use this to verify your regular expressions.
2. Regular Expression Desktop Tool
This is good for programmer who prefer desktop tools. This small Adobe Air application allow you to test different types of regular expression with help tips at each point.
If you are new to regular expression, then this is best for you as it not only help you write correct regular expressions, but also gives you many details about them at each stage.
In my workflow, I often practice start with desktop tool first. I try all possibilities until I get intended results. When I am satisfied with results, I open online tool, put my regular expression there and grab codes which I can directly paste in my programs.