Drupal list all content types and fields

drupal list content types

$content_types = node_get_types(); 
$output = ''; 
foreach($content_types as $content_type => $content_type_object) {
  $output .= "" . $content_type_object->name . ""; 
  $output .= ' '; 
  $fields = _content_type_info(); 
  $fields = $fields['content types'][$content_type]['fields']; 
  $ouput = ''; 
  foreach ($fields as $field_name=>$field) { 
    $output .= $field['widget']['label']; 
    $output .= ' '; 
  } 
}