表单验证 密码验证不能是纯数字 可以纯字母 可以字母与数字混用 有大用

{
    $this->load->library('form_validation');

    $this->form_validation->set_rules('password', "<span class='error'>密码</span>", 'required|min_length[6]|regex_match[/^(?!\d+$)[\da-zA-Z]*$/]|trim');
    $this->form_validation->set_rules('repassword', "<span class='error'>确认密码</span>", 'required|matches[password]');

    if ($this->form_validation->run() == FALSE)
    {
        $this->load->view('admin/users/modify', $this->_data);
        return ;
    }
    $this->load->view('admin/users/modify', $this->_data);


}