Form validation rules for regex_match

Question

I\'m trying to figure out what I\'m doing wrong with this validation rule because its saying this error.

Validation rule:

$this->form_validation-&         


        

Answer 1

Use following code its working fine at my end

$this->form_validation->set_rules('username', 'Username','trim|required|callback_username_check|regex_match[/^[a-z0-9]+$/]');