binary tree in c implementation

11 void insert(node ** tree, int val) {
12 node *temp = NULL;
13 if(!(*tree)) {
14   temp = (node *)malloc(sizeof(node));
15   temp->left = temp->right = NULL;
16   temp->data = val;
17   *tree = temp;
18   return;
19 }
20
21 if(val < (*tree)->data) {
22      insert(&(*tree)->left, val);
23   } else if(val > (*tree)->data) {
24     insert(&(*tree)->right, val);
25   }
26 }