How can I call form function in html? I have requirement in that I want to show a dropdown values. So to achieve this I created a form function with select type and returning the form. I want to display it in a html page. Here is what I have tried: 

function cart_confirmation_form($form, &amp;$formstate){

  $opt = array('Hi','Bye'); 
  $form['dropdown'] = array(
    '#title' =&gt; 'somethinfg',
    '#type' =&gt; 'select',
    '#options' =&gt; $opt,
  );
  return $form;
}
   function testing(){
     $message .= '&lt;div class="popup-related-tabs" style="float: left;" &gt;' . cart_confirmation_form($form, $formstate) . '&lt;/div&gt;';
      $message .= '&lt;div class="popup-related-titles" style="padding:15px;" id="popup-related-block"&gt;'.$form_message.'&lt;/div&gt;';
    drupal_set_message('&lt;div class="message-inner" style="padding:15px;"&gt;' . $message . '&lt;/div&gt;' );

}


This is not working, It says array to string conversion, form and formstate is undefined something like this. I know this is not correct way please suggest me the correct way to print values in dropdown.
Assuming testing() is a page callback, you want this:

function testing()
{
  $form = drupal_get_form('cart_confirmation_form')
  $output = '&lt;div class="popup-related-tabs" style="float: left;" &gt;' . render($form) . '&lt;/div&gt;';

  return $output;
}


Though personally I'd built it as a render array:

function testing()
{
  $page = array
  (
    '#prefix' =&gt; '&lt;div class="popup-related-tabs" style="float: left;" &gt;',
    '#suffix' =&gt; '&lt;/div&gt;',
    'form' =&gt; drupal_get_form('cart_confirmation_form')
  );

  return $page;
}