Drupal has a very neat feature for form validations. The form holds a flat array '#validate' that is simply a list of functions to be executed when validating the form in question. Our example validator for today will be the login form. The array looks like this by default.
Tuesday, November 27, 2012 - 03:24
Saturday, November 24, 2012 - 05:12
This is going to be a multi part article covering some aspects of the forms api in drupal 7 explaining some common tasks and their pitfalls when working with forms. Usually there is more than one way to get where you want to be.