Regular Expressions Tutorial: Getting Started

One More Exercise…

There are a lot of real-world examples of strings that you can validate with regular expressions. As a final exercise, try to untangle the following regular expression that validates an email address:

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?

It looks like a jumble of characters at first glance, but with your new-found knowledge (and the helpful links below) you’re one step closer to understanding it and becoming a master of regular expressions!

More Resources

Here is a short list of some useful resources about regular expressions:

• www.regular-expressions.info is an informative site by Jan Goyvaerts. He also has published some very comprehensive books on regular expressions.
• NSRegularExpression Class Reference is always your best reference for using NSRegularExpression API.
• For a quick test of a regex pattern, regexpal.com is very handy resource.

I hope you enjoyed this NSRegularExpression tutorial, and if you have any comments or questions, please join the forum discussion below!