Check out date in search box

If you're php savvy you can create a new module with the following function. If you're not sure on how to create a module, use the modulebuilder module. This code is untested (other than php validation) but should be near to working order. Replace the MYMODULE with your module name.

/**
 * Implementation of hook_form_alter
 */
function MYMODULE_form_alter(&$form, $form_state, $form_id) {
  if ($form_id == 'hotel_booking_widget_form') {
    $form['roomsearch']['checkout'] = array(
      '#prefix' => '<div class="bking-date">',
      '#type' => 'date_popup',
      '#title' => 'Check-Out Date',
      '#required' => TRUE,
      '#size' => 14,
      '#date_type' => DATE_ISO,
      '#date_timezone' => date_default_timezone_name(),
      '#date_format' => 'm/d/Y',
      '#date_year_range' => '-0:+1',
      '#suffix' => '</div>',
     ); 
     unset($form['roomsearch']['staylength']);
     if (isset($form['#validate']) && is_array($form['#validate'])) {
      array_unshift($form['#validate'], 'MYMODULE_validate_checkout');
    }
    else {
      $form['#validate'] = array('MYMODULE_validate_checkout');
    }
  }
}

/** 
 * Validation to switch the checkout back to staylength
 */
function MYMODULE_validate_checkout($form, &$form_state) {
    $nights = (strtotime($form_state['values']['checkout']) - strtotime($form_state['values']['checkin']))/ 86400; //86400 secs in day
   $form_state['values']['staylength'] = $nights;
}

Dear larowlan/Mr J

I have the same requirement. I tried as larowlan post, but it didn't work for me. Please help me with more details.
I created a module and add the given code, activated the module, but it didn't work. Pleae help
Thanks
Gamni