Regular expressions by example
Use the form button and check for each pattern if some kind of value is valid or not. This is just a regex example, there is much more you can do with regular expressions.
All patterns are optimized to use with the PHP function preg_match (note the leading and the trailing slash).
Related PHP functions:
Do you like to do more with regular expressions? Check the preg_match_all() PHP tutorial on my web development blog.