set_value, set_select, set_radio

[eluser]pickupman[/eluser]
[quote author="WanWizard" date="1274819719"]In principle every piece of user input requires validation, as it can be manipulated.
You can work around that by validating them with an empty rule set.[/quote]
+1...at least use

Code:

$this->form_validation->set_rules('field', 'field name', 'trim');

Trim may a little silly for radios and checkboxes, but you never know when some will manipulate your forms to be a little mischievous.