title: Codeigniter missing argument 1
body: <p>I'm learning to make a simple login through codeigniter, then I got an error like 
  <code>Missing argument 1 for C_login::login()</code> when I press the "login" button on my views without entering the username and password field.</p>
  
  <p>these are my controller, my IDE (netbeanPHP+CI framework) shows no error</p>
  
  <pre><code>&lt;?php
  class C_login extends CI_Controller{
  
  public function __construct() {
      parent::__construct();
      $this-&gt;load-&gt;model('m_login'); 
  }
  
  function index()
  {
      $this-&gt;form_validation-&gt;set_rules('username','trim|Username','required|exact_length[4]|xss_clean');
      $this-&gt;form_validation-&gt;set_rules('password','trim|Password','required|min_length[4]|max_length[40]|xss_clean|callback_login');
  
      if($this-&gt;form_validation-&gt;run() == false)
      {
          $this-&gt;load-&gt;view('login');
      }
      else
      {
          echo 'sukses validasi';
      }
  
  }
  
  function login($password)
  {
      $username = $this-&gt;input-&gt;post('username');
      $password = $this-&gt;input-&gt;post('password');
      $jabatan = $this-&gt;input-&gt;post('jabatan');
  
      $value = $this-&gt;m_login-&gt;cekpass($username,$password,$jabatan);
  
      if($value)
      {
          return true;
      }
      else
      {
          return false;
      }
  
  }
  
  
  }
   ?&gt;
  </code></pre>
  
  <p>and here is the model, i think my model is not showing any error</p>
  
  <pre><code>&lt;?php
  class M_login extends CI_Model{
  
  public function __construct() {
      parent::__construct();
  }
  
  function login ($username, $password, $jabatan)
  {
     $this-&gt;db-&gt;where('username',$username);
     $this-&gt;db-&gt;where('password',$password);
     $this-&gt;db-&gt;where('jabatan',$jabatan);
  
     $value = $this-&gt;db-&gt;get('ms_user');
  
     if($value-&gt;num_rows()&gt;0)
     {
         return true;
     }
     else
     {
         return false;
     }
  
  
  }
  }?&gt;
  </code></pre>