I found that the jsonlint sample did not free the memory for the DOM tree. The following is my implementation. This may be needed to show proper use of the API in real application.
static void tree_free(json_val_t* v) {
switch (v->type) {
case JSON_OBJECT_BEGIN:
for (int i = 0; i < v->length; i++) {
tree_free(v->u.object[i]->val);
free(v->u.object[i]->key);
free(v->u.object[i]);
}
free(v->u.object);
break;
case JSON_ARRAY_BEGIN:
for (int i = 0; i < v->length; i++)
tree_free(v->u.array[i]);
free(v->u.array);
break;
default:
free(v->u.data);
break;
}
free(v);
}
int main(int argc, char **argv)
{
// ...
if (use_tree) {
json_val_t *root_structure;
ret = do_tree(&config, argv[i], &root_structure);
if (ret)
exit(ret);
if (!verify)
print_tree(root_structure, output);
tree_free(root_structure); // <--
}
// ...
} 
I found that the jsonlint sample did not free the memory for the DOM tree. The following is my implementation. This may be needed to show proper use of the API in real application.