Testing Regular Expressions with Color Highlighting

Discovered a great website today while working on a complex Regular Expression: RegExPal.com. The site provides color code highlighting for RegEx syntax, including real-time evaluation of test data. If you, for instance, forget to include a closing or opening parenthesis for a group inside the regular expression, the orphaned parenthesis will be highlighted in red for easy identification of the error.

Here is a quick screenshot of some of the highlighting in action:
RegExPal Screenshot

Be advised that this is based on JavaScript regular expressions, which are comparable to the PERL compatible RegEx functions, such as preg_replace() and preg_match(). It’s a good idea to get familiar with this syntax, as ereg() and eregi() style functions will be removed from PHP6 when it is released, sometime in the future. Make sure to also checkout the Regular Expressions Cookbook contributed to by the author of RegExPal.com.