Example of PHP-framework?
The best-known are Zend, CodeIgniter, CakePHP etc. 'Recently' there are a few new competitors that aim to be more lightweight: Kohana, Yii etc.
I'll be diving into Kohana the moment I feel at ease using objects. I am now struggling somewhat to make the change...
If you want a validation routine, then I guess you should look into the official documentation for PHP Filters. They contain pre-built functions to validate and even sanitize different data formats (strings, numeric, email, url, etc). The examples that are given in that section of the documentation are very good...