Can't set default values on select list

The short answer is that your array of select options needs to be an associative array consisting of a $key => $value pairs where both the $key and $value contain the option value.

If you hand an indexed array of options to a select list, it will produce select options that use the index as the value. For example, this:

$options = array('Red', 'Green', 'Blue');

$form['example']['colors'] = array(
  '#title' => t('Colors'),
  '#type' => 'select',
  '#options' => $options,
  '#default_value' => 'Red',
);

will produce this:

<select name="colors" class="form-select" id="edit-colors" >
  <option value="0"></option>
  <option value="1">Red</option>
  <option value="2">Green</option>
  <option value="3">Blue</option>
</select>

The '#default_value' of 'Red' isn't in the list of values so it won't display 'Red' as the selected choice.

The correct way to do this is to set an associative array of options so that this:

$options = array('Red' => 'Red', 'Green' => 'Green', 'Blue' => 'Blue');

$form['example']['colors'] = array(
  '#title' => t('Colors'),
  '#type' => 'select',
  '#options' => $options,
  '#default_value' => 'Red',
);

will produce this:

<select name="colors" class="form-select" id="edit-colors" >
  <option value=""></option>
  <option value="Red" selected="selected">Red</option>
  <option value="Green">Green</option>
  <option value="Blue">Blue</option>
</select>

The 'Red' option will be marked as 'selected' because the '#default_value' of 'Red' is in the list of values and can therefore be set as 'selected'.

Hope that helps.

How do you do this in code? I have a module where I read the CCK form in, and then (if user is logged in), prefill the fields with the users content profile. This works fine for textfields, but for the life of me I have not figured out how to set default_value for select.

function orderonline_form ($form_state) {

	// Load in the Online Order form elements
	require("modules/node/node.pages.inc");
	$nodeType = 'online_order';
	$form_id = $nodeType . '_node_form';
	 	
	$node = array('type' => $nodeType, 'uid' => $GLOBALS['user']->uid, 'name' => $GLOBALS['user']->uid);
	$form = drupal_retrieve_form('online_order_node_form',$form_state,$node);
	drupal_prepare_form($form_id,$form,$form_state);


	// If the User is logged in, and has a content profile, we will preload the order form for them
	$userid = $GLOBALS['user']->uid;
	if ($userid > 0) {
		$view = views_get_view('getCustomerProfileByUID');
		$view->set_arguments($userid);
		$view->execute();

		if (count($view->result)) {
//This doesnt work as it is a select - eg Mr., Mrs. Ms, Dr., etc.
			$form['group_aboutyou']['field_custprefix']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custprefix_field_custprefix_value,);
//These work as they are textfields
			$form['group_aboutyou']['field_custfirstname']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custfirstname_field_custfirstname_value;
			$form['group_aboutyou']['field_custmi']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custmi_field_custmi_value;
			$form['group_aboutyou']['field_custlastname']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custlastname_field_custlastname_value;
			$form['group_aboutyou']['field_custsuffix']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custsuffix_field_custsuffix_value;
			$form['group_aboutyou']['field_custtitle']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custtitle_field_custtitle_value;
			$form['group_aboutyou']['field_custorganization']['0']['#default_value']['value'] = $view->result[0]->node_data_field_custorganization_field_custorganization_value;
		}
		
	} 

//echo "<PRE>";
//print_r($form);
//echo "</PRE>";
	return $form;
}

Sorry for being late but ...
That associative array does not seem a good way to refer selectable options.
What if I have something like:

colors ('High Red', 'Light grey', ......);

The expected here would be to index colors such as a database model would do :
(1=>'High Red', 'Light grey', ... )

In order to present the text in the select element but choose it thru its index.
And as you say, this ain't valid ? (indeed default_value it's not working for me)

Let's don't resurrect a two year old issue for another version and try to make any sense out of it. If you have a question about the current code create a new issue with enough detail to tell what you're talking about. No clue what your question is.

Please do not change subject and version (I reset them). You should really post a new issue, not use an old closed one.

Drupal 7 Form API select element
case: how to set default_value for a select form element (month field) so that Oct is selected as defult ?
step 1: for eg: $month=10;

step 2: $monthOptions=array("1"=>"january",
"2"=>"feb","3"=>"mar","4"=>"apr","5"=>"may",
"6"=>"jun","7"=>"jul","8"=>"aug","9"=>"sep",
"10"=>"oct","11"=>"nov","12"=>"dec");
Step 3:
$form['elementName']['month']=array(
'#type'=> 'select',
'#title' => 'Month',
'#required' => 'true',
'#options' => $monthOptions,
'#default_value' => $month,

);

#7 is correct