checkbox type in form how i can knowing if the checkbox is checked or not on the form


function darksite_config_page() {
  $form['darksite_status'] = array(
    '#title' => t('Enable pop up screen'),
    '#description' => t('When enabled, a pop up screen will be displayed on the home page.'),
    '#type' => 'checkbox',
    '#default_value' => variable_get('darksite_status', 0)
  );

  return system_settings_form($form);
}
Like so:

if (variable_get('darksite_status', 0)) {
  // Yes.
}
else {
  // No.
}