Validating text field entries

[micmac]

Hi Guys,
I've created a simple location locator script. Everything works fine, but now i want to add a few features.
For example, if someone types in only a couple of numbers in the zip/postal code input text field and not the required four numbers i want it to show an error message. At the same time this should also check that the entry is a number and not a letter.
Can anyone direct me in what to do in this situation?

Cheers,
maccam

[Anon]

This kind of pattern matching is what "regular expressions" are all about. They do all you want and a whole bunch more.

Too much to explain here, do a bit of research. RE's are pretty much the same in php, mysql, Javascript, perl, python, and other implementations so it's really worth taking the time to learn.

A good book is "Mastering Regular Expressions":

http://www.oreilly.com/catalog/regex2/

[sp0rk]

Checking strlen and is_numerical should do the trick.