Example of displaying multiple checkboxes, with one value selected

  1. $form['option_occassions'] = array(
  2.    '#type' => 'checkboxes',
  3.   '#title' => t('Associated Occassions'),
  4.    '#options' => array(
  5.     1 => "Formal",
  6.     2 => "Social",
  7.     3 => "Xmas",
  8.     4 => "Hens",
  9.     5 => "14th Birthday",
  10.     6 => "15th Birthday",
  11.     7 => "16th Birthday",
  12.     8 => "17th Birthday",
  13.     9 => "18th Birthday",
  14.     10 => "21st Birthday",
  15.     11 => "20 Something Birthday",
  16.     12 => "30 Something Birthday",
  17.     13 => "40 Something Birthday",
  18.     14 => "50 Something Birthday",
  19.     15 => "60 Soemthing Birthday",
  20. ),
  21.    '#multiple' => true,
  22.    '#default_value' => array(
  23.     1 => 4,
  24. ),
  25.    );