Validating Select Drop Down Array in PHP

Question

I have the following to generate a state drop down on a form:

$states = array('State', 'Alabama', 'Alaska', 'Arizona', 'Arkansas');
echo "<select name='choose_state'>\n";
foreach ($states as $key => $state)
{echo "<option value='$key'>$state</option>\n";}
echo "</select>";

How would I go about making sure a user
1) only selects one of the options in the array
2) doesn't select the default value? ([0]=> string(5) "State")

edit: validate in php, this is for a form collecting user information before posting to a db
I tried using in_array and got stuck trying to exclude the default value

Answer 1

I think you're missing some checks. You should never rely on what is exacly posted, and always perform thorough checking:

$chosen_state = null;

if (array_key_exists('choose_state', $_POST))
{
  $choose_state = $_POST['choose_state'];
  if (array_key_exists($choose_state, $states) && $choose_state > 0)
  {
    // Value does actually exist in array and is not item 0.
    $chosen_state = $states[$chose_state]);
  }
}