This should do it..
$foo = isset($_POST['foo']) ? $_POST['foo'] : '';
$options = array('One'=>1, 'Two'=>2, 'Three'=>3);
echo '<select name="foo">';
foreach ($options as $k=>$v) {
$sel = ($foo == $v ? ' selected="selected"' : '');
echo '<option value="'.$v.'"'.$sel.'>'.$k.'</option>';
}
echo '</select>';
If you are wondering about those $foo and $sel, you can do them in traditional way with if .. else .. like:
if (isset($_POST['foo'])) $foo = $_POST['foo']; else $foo = '';
EDIT: too slow 🙂