PHP and MySQL

10.3    Application Examples

In this section, we will show you some useful applications for regular expressions—for form validation, for example.

Note

You will find further examples of regular expressions in this book—for example, in the completeness check in Chapter 13. A check of email addresses is carried out there. This difficult topic is also discussed at http://s-prs.co/v602216.

10.3.1    Zip Codes

The verification of zip codes is very simple. A US zip code always consists of five digits. You can check this as follows:

$reg = "/^\d{5}$/";  

Additionally a zip code can have a second part with four digits. As separator should be a space or a hyphen possible, after this there are four digits:

$reg = "/^(\d{5})(?:[-\s](\d{4}))?$/";  

So you ...