Input_Item::validate — Validates the specified data.

public mixed Input_Item::validate ( string $method, mixed $data [, mixed $options] )

1. method
   A valid Validation method.
2. data
   The data which will be validated.
3. options
   Options sent to the validation method. Only required in special cases.

If $data is not set, NULL will be returned. FALSE is returned on validation failure and TRUE returns of everything's OK.

http://example.com/?email=someemail@host.com

if ($input->get ('email')->validate ('valid_email')) {
    // 'email' is a real Email address
}

Validation.